diff --git a/config/dev.exs b/config/dev.exs
index b4fb15af..49e3ca53 100644
--- a/config/dev.exs
+++ b/config/dev.exs
@@ -52,7 +52,8 @@ config :towerops, Oban,
     pollers: 50,
     # Device monitoring jobs - health checks
     monitors: 50,
-    maintenance: 5
+    maintenance: 5,
+    weather: 2
   ],
   plugins: [
     # Cron jobs for periodic maintenance tasks
diff --git a/config/runtime.exs b/config/runtime.exs
index e9572c85..fb11dfd4 100644
--- a/config/runtime.exs
+++ b/config/runtime.exs
@@ -164,7 +164,8 @@ if config_env() == :prod do
       monitors: 50,
       # Service checks - HTTP/TCP/DNS
       checks: 50,
-      maintenance: 5
+      maintenance: 5,
+      weather: 2
     ],
     plugins: [
       # Cron jobs for periodic maintenance tasks
@@ -339,4 +340,9 @@ if config_env() == :prod do
   # Timezone data is updated through dependency updates instead
   # This prevents crashes when network timeouts occur during automatic updates
   config :tzdata, :autoupdate, :disabled
+
+  # OpenWeatherMap API key for site weather data
+  if owm_key = System.get_env("OPENWEATHERMAP_API_KEY") do
+    config :towerops, :openweathermap_api_key, owm_key
+  end
 end
diff --git a/lib/towerops/maintenance.ex b/lib/towerops/maintenance.ex
new file mode 100644
index 00000000..f411b1a9
--- /dev/null
+++ b/lib/towerops/maintenance.ex
@@ -0,0 +1,162 @@
+defmodule Towerops.Maintenance do
+  @moduledoc """
+  Context for managing maintenance windows.
+
+  Maintenance windows suppress alerts for devices, sites, or entire organizations
+  during scheduled maintenance periods.
+  """
+
+  import Ecto.Query
+
+  alias Towerops.Devices.Device
+  alias Towerops.Maintenance.MaintenanceWindow
+  alias Towerops.Repo
+
+  @preloads [:organization, :site, :device, :created_by]
+
+  def create_window(attrs) do
+    %MaintenanceWindow{}
+    |> MaintenanceWindow.changeset(attrs)
+    |> Repo.insert()
+  end
+
+  def update_window(%MaintenanceWindow{} = window, attrs) do
+    window
+    |> MaintenanceWindow.changeset(attrs)
+    |> Repo.update()
+  end
+
+  def delete_window(%MaintenanceWindow{} = window) do
+    Repo.delete(window)
+  end
+
+  def get_window!(id) do
+    MaintenanceWindow
+    |> Repo.get!(id)
+    |> Repo.preload(@preloads)
+  end
+
+  def list_windows(organization_id, opts \\ []) do
+    now = DateTime.utc_now()
+
+    MaintenanceWindow
+    |> where([w], w.organization_id == ^organization_id)
+    |> apply_filter(opts[:filter], now)
+    |> order_by([w], desc: w.starts_at)
+    |> Repo.all()
+    |> Repo.preload(@preloads)
+  end
+
+  defp apply_filter(query, :active, now) do
+    where(query, [w], w.starts_at <= ^now and w.ends_at >= ^now)
+  end
+
+  defp apply_filter(query, :upcoming, now) do
+    where(query, [w], w.starts_at > ^now)
+  end
+
+  defp apply_filter(query, :past, now) do
+    where(query, [w], w.ends_at < ^now)
+  end
+
+  defp apply_filter(query, _, _now), do: query
+
+  @doc """
+  Checks if a device is currently in a maintenance window.
+  Checks direct device windows, site windows, and org-wide windows.
+  """
+  def device_in_maintenance?(device_id) do
+    case active_windows_for_device(device_id) do
+      [] -> false
+      _ -> true
+    end
+  end
+
+  @doc """
+  Checks if a site is currently in a maintenance window.
+  """
+  def site_in_maintenance?(site_id) do
+    now = DateTime.utc_now()
+
+    MaintenanceWindow
+    |> where([w], w.site_id == ^site_id and is_nil(w.device_id))
+    |> where([w], w.starts_at <= ^now and w.ends_at >= ^now)
+    |> where([w], w.suppress_alerts == true)
+    |> Repo.exists?()
+  end
+
+  @doc """
+  Returns all active maintenance windows affecting a device.
+  Checks: direct device match, site match, and org-wide windows.
+  """
+  def active_windows_for_device(device_id) do
+    now = DateTime.utc_now()
+
+    device = Repo.get!(Device, device_id)
+
+    active_base =
+      MaintenanceWindow
+      |> where([w], w.organization_id == ^device.organization_id)
+      |> where([w], w.starts_at <= ^now and w.ends_at >= ^now)
+      |> where([w], w.suppress_alerts == true)
+
+    # Direct device windows
+    direct = where(active_base, [w], w.device_id == ^device_id)
+
+    # Site windows (if device has a site)
+    site_query =
+      if device.site_id do
+        where(active_base, [w], w.site_id == ^device.site_id and is_nil(w.device_id))
+      else
+        where(active_base, [w], false)
+      end
+
+    # Org-wide windows
+    org_wide = where(active_base, [w], is_nil(w.site_id) and is_nil(w.device_id))
+
+    direct_results = Repo.all(direct)
+    site_results = Repo.all(site_query)
+    org_results = Repo.all(org_wide)
+
+    (direct_results ++ site_results ++ org_results)
+    |> Enum.uniq_by(& &1.id)
+  end
+
+  @doc """
+  Returns all active maintenance windows for an organization.
+  """
+  def active_windows_for_org(organization_id) do
+    now = DateTime.utc_now()
+
+    MaintenanceWindow
+    |> where([w], w.organization_id == ^organization_id)
+    |> where([w], w.starts_at <= ^now and w.ends_at >= ^now)
+    |> Repo.all()
+    |> Repo.preload(@preloads)
+  end
+
+  @doc """
+  Returns the name of the active maintenance window for a device or site, or nil.
+  Accepts a %Device{} or %Site{} struct.
+  """
+  def maintenance_badge(%Device{} = device) do
+    case active_windows_for_device(device.id) do
+      [window | _] -> window.name
+      [] -> nil
+    end
+  end
+
+  def maintenance_badge(%Towerops.Sites.Site{} = site) do
+    now = DateTime.utc_now()
+
+    MaintenanceWindow
+    |> where([w], w.site_id == ^site.id and is_nil(w.device_id))
+    |> where([w], w.starts_at <= ^now and w.ends_at >= ^now)
+    |> where([w], w.suppress_alerts == true)
+    |> limit(1)
+    |> select([w], w.name)
+    |> Repo.one()
+  end
+
+  def maintenance_badge(_), do: nil
+end
diff --git a/lib/towerops/maintenance/maintenance_window.ex b/lib/towerops/maintenance/maintenance_window.ex
new file mode 100644
index 00000000..7ab4a78f
--- /dev/null
+++ b/lib/towerops/maintenance/maintenance_window.ex
@@ -0,0 +1,65 @@
+defmodule Towerops.Maintenance.MaintenanceWindow do
+  @moduledoc """
+  Schema for maintenance windows that suppress alerts during scheduled maintenance.
+
+  A window can target:
+  - A specific device (device_id set)
+  - All devices at a site (site_id set, device_id nil)
+  - All devices in an org (both nil)
+  """
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  alias Towerops.Accounts.User
+  alias Towerops.Devices.Device
+  alias Towerops.Organizations.Organization
+  alias Towerops.Sites.Site
+
+  @primary_key {:id, :binary_id, autogenerate: true}
+  @foreign_key_type :binary_id
+  schema "maintenance_windows" do
+    field :name, :string
+    field :reason, :string
+    field :starts_at, :utc_datetime
+    field :ends_at, :utc_datetime
+    field :recurring, :boolean, default: false
+    field :recurrence_rule, :string
+    field :suppress_alerts, :boolean, default: true
+
+    belongs_to :organization, Organization
+    belongs_to :site, Site
+    belongs_to :device, Device
+    belongs_to :created_by, User
+
+    timestamps()
+  end
+
+  @required_fields ~w(name starts_at ends_at organization_id created_by_id)a
+  @optional_fields ~w(reason site_id device_id recurring recurrence_rule suppress_alerts)a
+
+  def changeset(window, attrs) do
+    window
+    |> cast(attrs, @required_fields ++ @optional_fields)
+    |> validate_required(@required_fields)
+    |> validate_length(:name, max: 255)
+    |> validate_length(:reason, max: 1000)
+    |> validate_ends_after_starts()
+    |> foreign_key_constraint(:organization_id)
+    |> foreign_key_constraint(:site_id)
+    |> foreign_key_constraint(:device_id)
+    |> foreign_key_constraint(:created_by_id)
+    |> check_constraint(:ends_at, name: :ends_at_after_starts_at, message: "must be after starts_at")
+  end
+
+  defp validate_ends_after_starts(changeset) do
+    starts_at = get_field(changeset, :starts_at)
+    ends_at = get_field(changeset, :ends_at)
+
+    if starts_at && ends_at && DateTime.compare(ends_at, starts_at) != :gt do
+      add_error(changeset, :ends_at, "must be after starts_at")
+    else
+      changeset
+    end
+  end
+end
diff --git a/lib/towerops/sites.ex b/lib/towerops/sites.ex
index 15916c30..eb1c140c 100644
--- a/lib/towerops/sites.ex
+++ b/lib/towerops/sites.ex
@@ -11,6 +11,18 @@ defmodule Towerops.Sites do
   alias Towerops.Repo
   alias Towerops.Sites.Site
 
+  @doc """
+  Lists all sites across all organizations that have geographic coordinates set.
+  Used by the weather sync worker to fetch weather data.
+  """
+  def list_sites_with_coordinates do
+    from(s in Site,
+      where: not is_nil(s.latitude) and not is_nil(s.longitude),
+      select: s
+    )
+    |> Repo.all()
+  end
+
   @doc """
   Returns the list of sites for an organization.
   Ordered by custom display_order (if set), then alphabetically by name.
diff --git a/lib/towerops/weather.ex b/lib/towerops/weather.ex
new file mode 100644
index 00000000..2e2e1fa2
--- /dev/null
+++ b/lib/towerops/weather.ex
@@ -0,0 +1,235 @@
+defmodule Towerops.Weather do
+  @moduledoc """
+  Weather context for site-correlated weather data.
+
+  Provides current conditions, historical observations, and weather alerts
+  tied to tower site locations. Used for outage correlation and operational
+  awareness.
+  """
+
+  import Ecto.Query
+
+  alias Towerops.Repo
+  alias Towerops.Weather.Alert, as: WeatherAlert
+  alias Towerops.Weather.Client
+  alias Towerops.Weather.Observation
+
+  require Logger
+
+  # ── Observations ─────────────────────────────────────────────────────
+
+  @doc """
+  Records a weather observation for a site.
+  """
+  def create_observation(attrs) do
+    %Observation{}
+    |> Observation.changeset(attrs)
+    |> Repo.insert()
+  end
+
+  @doc """
+  Gets the latest weather observation for a site.
+  """
+  def latest_observation(site_id) do
+    Observation
+    |> where(site_id: ^site_id)
+    |> order_by(desc: :observed_at)
+    |> limit(1)
+    |> Repo.one()
+  end
+
+  @doc """
+  Gets the latest weather observation for each site in an organization.
+  Returns a map of site_id => observation.
+  """
+  def latest_observations_for_org(organization_id) do
+    # Subquery to get latest observation per site
+    latest_ids =
+      from(o in Observation,
+        join: s in assoc(o, :site),
+        where: s.organization_id == ^organization_id,
+        group_by: o.site_id,
+        select: %{site_id: o.site_id, max_id: max(o.id)}
+      )
+
+    from(o in Observation,
+      join: l in subquery(latest_ids),
+      on: o.id == l.max_id
+    )
+    |> Repo.all()
+    |> Map.new(fn obs -> {obs.site_id, obs} end)
+  end
+
+  @doc """
+  Gets weather observations for a site within a time range.
+  Useful for correlating weather with outage events.
+  """
+  def observations_for_site(site_id, opts \\ []) do
+    after_time = opts[:after] || DateTime.add(DateTime.utc_now(), -24, :hour)
+    limit = opts[:limit] || 100
+
+    Observation
+    |> where(site_id: ^site_id)
+    |> where([o], o.observed_at >= ^after_time)
+    |> order_by(desc: :observed_at)
+    |> limit(^limit)
+    |> Repo.all()
+  end
+
+  @doc """
+  Cleans up old weather observations. Keeps the last `keep_days` days.
+  """
+  def cleanup_old_observations(keep_days \\ 30) do
+    cutoff = DateTime.add(DateTime.utc_now(), -keep_days, :day)
+
+    {count, _} =
+      from(o in Observation, where: o.observed_at < ^cutoff)
+      |> Repo.delete_all()
+
+    Logger.info("Cleaned up #{count} old weather observations")
+    {:ok, count}
+  end
+
+  # ── Weather Alerts ───────────────────────────────────────────────────
+
+  @doc """
+  Creates or updates a weather alert for a site.
+  """
+  def upsert_alert(attrs) do
+    %WeatherAlert{}
+    |> WeatherAlert.changeset(attrs)
+    |> Repo.insert()
+  end
+
+  @doc """
+  Gets active weather alerts for a site (not yet expired).
+  """
+  def active_alerts_for_site(site_id) do
+    now = DateTime.utc_now()
+
+    WeatherAlert
+    |> where(site_id: ^site_id)
+    |> where([a], is_nil(a.ends_at) or a.ends_at > ^now)
+    |> order_by(desc: :inserted_at)
+    |> Repo.all()
+  end
+
+  @doc """
+  Gets active weather alerts for all sites in an organization.
+  """
+  def active_alerts_for_org(organization_id) do
+    now = DateTime.utc_now()
+
+    from(a in WeatherAlert,
+      join: s in assoc(a, :site),
+      where: s.organization_id == ^organization_id,
+      where: is_nil(a.ends_at) or a.ends_at > ^now,
+      order_by: [desc: a.inserted_at],
+      preload: [:site]
+    )
+    |> Repo.all()
+  end
+
+  # ── Fetching ─────────────────────────────────────────────────────────
+
+  @doc """
+  Fetches and stores current weather for a site.
+  Requires the site to have latitude and longitude set.
+  """
+  def fetch_and_store(site) do
+    if site.latitude && site.longitude do
+      case Client.get_current_weather(site.latitude, site.longitude) do
+        {:ok, data} ->
+          attrs = Observation.from_owm(site.id, data)
+          create_observation(attrs)
+
+        {:error, reason} ->
+          Logger.warning("Failed to fetch weather for site #{site.name}: #{inspect(reason)}")
+          {:error, reason}
+      end
+    else
+      {:error, :no_coordinates}
+    end
+  end
+
+  # ── Correlation Helpers ──────────────────────────────────────────────
+
+  @doc """
+  Checks if there was severe weather at a site around a given time.
+  Returns observations with high wind, heavy rain, or storms.
+
+  Useful for determining if an outage was likely weather-related.
+  """
+  def severe_weather_near?(site_id, time, window_minutes \\ 60) do
+    start_time = DateTime.add(time, -window_minutes, :minute)
+    end_time = DateTime.add(time, window_minutes, :minute)
+
+    observations =
+      Observation
+      |> where(site_id: ^site_id)
+      |> where([o], o.observed_at >= ^start_time and o.observed_at <= ^end_time)
+      |> Repo.all()
+
+    Enum.any?(observations, &severe?/1)
+  end
+
+  @doc """
+  Returns a weather summary for a site at a point in time.
+  Finds the closest observation within 30 minutes.
+  """
+  def weather_at(site_id, time) do
+    start_time = DateTime.add(time, -30, :minute)
+    end_time = DateTime.add(time, 30, :minute)
+
+    Observation
+    |> where(site_id: ^site_id)
+    |> where([o], o.observed_at >= ^start_time and o.observed_at <= ^end_time)
+    |> order_by([o], fragment("ABS(EXTRACT(EPOCH FROM ? - ?))", o.observed_at, ^time))
+    |> limit(1)
+    |> Repo.one()
+  end
+
+  @doc """
+  Determines if an observation represents severe weather conditions.
+
+  Thresholds relevant to WISP operations:
+  - Wind > 15 m/s (33 mph) — affects radio alignment
+  - Wind gusts > 20 m/s (45 mph) — risk of hardware damage
+  - Rain > 10mm/h — signal attenuation on wireless links
+  - Thunderstorm conditions
+  - Snow > 5mm/h — ice loading on equipment
+  """
+  def severe?(%Observation{} = obs) do
+    cond do
+      (obs.wind_speed_ms || 0) > 15 -> true
+      (obs.wind_gust_ms || 0) > 20 -> true
+      (obs.rain_1h_mm || 0) > 10 -> true
+      (obs.snow_1h_mm || 0) > 5 -> true
+      obs.condition in ["Thunderstorm"] -> true
+      true -> false
+    end
+  end
+
+  def severe?(_), do: false
+
+  @doc """
+  Returns a severity level for weather conditions.
+  :clear, :mild, :moderate, :severe
+  """
+  def severity(%Observation{} = obs) do
+    cond do
+      (obs.wind_gust_ms || 0) > 25 -> :severe
+      obs.condition in ["Thunderstorm"] -> :severe
+      (obs.rain_1h_mm || 0) > 20 -> :severe
+      (obs.wind_speed_ms || 0) > 15 -> :moderate
+      (obs.wind_gust_ms || 0) > 20 -> :moderate
+      (obs.rain_1h_mm || 0) > 10 -> :moderate
+      (obs.snow_1h_mm || 0) > 5 -> :moderate
+      obs.condition in ["Rain", "Drizzle", "Snow"] -> :mild
+      (obs.clouds_pct || 0) > 80 -> :mild
+      true -> :clear
+    end
+  end
+
+  def severity(_), do: :clear
+end
diff --git a/lib/towerops/weather/alert.ex b/lib/towerops/weather/alert.ex
new file mode 100644
index 00000000..4959cbc8
--- /dev/null
+++ b/lib/towerops/weather/alert.ex
@@ -0,0 +1,33 @@
+defmodule Towerops.Weather.Alert do
+  @moduledoc """
+  Severe weather alert associated with a site.
+  """
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  alias Towerops.Sites.Site
+
+  @primary_key {:id, :binary_id, autogenerate: true}
+  @foreign_key_type :binary_id
+  schema "weather_alerts" do
+    field :event, :string
+    field :sender, :string
+    field :description, :string
+    field :starts_at, :utc_datetime
+    field :ends_at, :utc_datetime
+    field :tags, {:array, :string}, default: []
+    field :severity, :string
+
+    belongs_to :site, Site
+
+    timestamps(type: :utc_datetime)
+  end
+
+  def changeset(alert, attrs) do
+    alert
+    |> cast(attrs, [:site_id, :event, :sender, :description, :starts_at, :ends_at, :tags, :severity])
+    |> validate_required([:site_id, :event])
+    |> foreign_key_constraint(:site_id)
+  end
+end
diff --git a/lib/towerops/weather/client.ex b/lib/towerops/weather/client.ex
new file mode 100644
index 00000000..cfc02ede
--- /dev/null
+++ b/lib/towerops/weather/client.ex
@@ -0,0 +1,77 @@
+defmodule Towerops.Weather.Client do
+  @moduledoc """
+  OpenWeatherMap API client.
+
+  Uses the free Current Weather Data API (2.5) which allows 60 calls/min.
+  Fetches weather by latitude/longitude — perfect for tower site locations.
+  """
+
+  require Logger
+
+  @base_url "https://api.openweathermap.org/data/2.5"
+
+  @doc """
+  Fetches current weather for the given coordinates.
+
+  Returns `{:ok, map}` with the raw OWM response or `{:error, reason}`.
+  """
+  def get_current_weather(lat, lon, opts \\ []) do
+    api_key = opts[:api_key] || api_key()
+
+    if is_nil(api_key) or api_key == "" do
+      {:error, :no_api_key}
+    else
+      url = "#{@base_url}/weather"
+
+      req_opts =
+        [
+          url: url,
+          params: [
+            lat: lat,
+            lon: lon,
+            appid: api_key
+          ]
+        ]
+        |> maybe_add_test_plug(opts)
+
+      case Req.get(req_opts) do
+        {:ok, %Req.Response{status: 200, body: body}} ->
+          {:ok, body}
+
+        {:ok, %Req.Response{status: 401}} ->
+          {:error, :invalid_api_key}
+
+        {:ok, %Req.Response{status: 429}} ->
+          {:error, :rate_limited}
+
+        {:ok, %Req.Response{status: status, body: body}} ->
+          Logger.warning("OWM API error", status: status, body: inspect(body))
+          {:error, {:api_error, status}}
+
+        {:error, reason} ->
+          Logger.warning("OWM API request failed", error: inspect(reason))
+          {:error, reason}
+      end
+    end
+  end
+
+  @doc """
+  Tests if the API key is valid by making a minimal request.
+  """
+  def test_connection(api_key) do
+    # Use a known location (London) for the test
+    get_current_weather(51.5074, -0.1278, api_key: api_key)
+  end
+
+  defp api_key do
+    Application.get_env(:towerops, :openweathermap_api_key)
+  end
+
+  defp maybe_add_test_plug(req_opts, opts) do
+    if opts[:plug] do
+      Keyword.put(req_opts, :plug, opts[:plug])
+    else
+      req_opts
+    end
+  end
+end
diff --git a/lib/towerops/weather/observation.ex b/lib/towerops/weather/observation.ex
new file mode 100644
index 00000000..e95a53f9
--- /dev/null
+++ b/lib/towerops/weather/observation.ex
@@ -0,0 +1,110 @@
+defmodule Towerops.Weather.Observation do
+  @moduledoc """
+  Weather observation for a site at a point in time.
+
+  Stores current weather conditions fetched from OpenWeatherMap,
+  tied to a site's geographic coordinates.
+  """
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  alias Towerops.Sites.Site
+
+  @primary_key {:id, :binary_id, autogenerate: true}
+  @foreign_key_type :binary_id
+  schema "weather_observations" do
+    field :condition, :string
+    field :condition_detail, :string
+    field :icon, :string
+    field :temperature_c, :float
+    field :feels_like_c, :float
+    field :humidity, :integer
+    field :pressure_hpa, :integer
+    field :visibility_m, :integer
+
+    field :wind_speed_ms, :float
+    field :wind_gust_ms, :float
+    field :wind_deg, :integer
+
+    field :rain_1h_mm, :float
+    field :snow_1h_mm, :float
+    field :clouds_pct, :integer
+
+    field :raw, :map
+
+    field :observed_at, :utc_datetime
+
+    belongs_to :site, Site
+
+    timestamps(type: :utc_datetime)
+  end
+
+  @cast_fields [
+    :site_id,
+    :condition,
+    :condition_detail,
+    :icon,
+    :temperature_c,
+    :feels_like_c,
+    :humidity,
+    :pressure_hpa,
+    :visibility_m,
+    :wind_speed_ms,
+    :wind_gust_ms,
+    :wind_deg,
+    :rain_1h_mm,
+    :snow_1h_mm,
+    :clouds_pct,
+    :raw,
+    :observed_at
+  ]
+
+  def changeset(observation, attrs) do
+    observation
+    |> cast(attrs, @cast_fields)
+    |> validate_required([:site_id, :observed_at])
+    |> foreign_key_constraint(:site_id)
+  end
+
+  @doc """
+  Parses an OpenWeatherMap current weather API response into observation attrs.
+  """
+  def from_owm(site_id, %{} = data) do
+    weather = List.first(data["weather"] || []) || %{}
+    main = data["main"] || %{}
+    wind = data["wind"] || %{}
+    rain = data["rain"] || %{}
+    snow = data["snow"] || %{}
+    clouds = data["clouds"] || %{}
+
+    observed_at =
+      case data["dt"] do
+        ts when is_integer(ts) -> DateTime.from_unix!(ts)
+        _ -> DateTime.utc_now(:second)
+      end
+
+    %{
+      site_id: site_id,
+      condition: weather["main"],
+      condition_detail: weather["description"],
+      icon: weather["icon"],
+      temperature_c: kelvin_to_celsius(main["temp"]),
+      feels_like_c: kelvin_to_celsius(main["feels_like"]),
+      humidity: main["humidity"],
+      pressure_hpa: main["pressure"],
+      visibility_m: data["visibility"],
+      wind_speed_ms: wind["speed"],
+      wind_gust_ms: wind["gust"],
+      wind_deg: wind["deg"],
+      rain_1h_mm: rain["1h"],
+      snow_1h_mm: snow["1h"],
+      clouds_pct: clouds["all"],
+      raw: data,
+      observed_at: observed_at
+    }
+  end
+
+  defp kelvin_to_celsius(nil), do: nil
+  defp kelvin_to_celsius(k) when is_number(k), do: Float.round(k - 273.15, 1)
+end
diff --git a/lib/towerops/workers/device_monitor_worker.ex b/lib/towerops/workers/device_monitor_worker.ex
index b7e75aa1..7b0619ed 100644
--- a/lib/towerops/workers/device_monitor_worker.ex
+++ b/lib/towerops/workers/device_monitor_worker.ex
@@ -17,6 +17,7 @@ defmodule Towerops.Workers.DeviceMonitorWorker do
   alias Towerops.Agents
   alias Towerops.Alerts
   alias Towerops.Devices
+  alias Towerops.Maintenance
   alias Towerops.Monitoring
   alias Towerops.PagerDuty.Notifier
   alias Towerops.Snmp.Client
@@ -196,11 +197,21 @@ defmodule Towerops.Workers.DeviceMonitorWorker do
     if Alerts.has_active_alert?(device.id, :device_down) do
       :ok
     else
-      create_device_down_alert(device, now)
+      if Maintenance.device_in_maintenance?(device.id) do
+        Logger.info("Device #{device.id} (#{device.name}) is down but in maintenance window — suppressing alert")
+        :ok
+      else
+        create_device_down_alert(device, now)
+      end
     end
   end
 
   defp create_device_down_alert(device, now) do
+    if Maintenance.device_in_maintenance?(device.id) do
+      require Logger
+      Logger.info("Device #{device.id} (#{device.name}) alert suppressed by maintenance window (safety net)")
+      :ok
+    else
     alert_message = get_down_alert_message(device)
 
     {:ok, alert} =
@@ -219,6 +230,7 @@ defmodule Towerops.Workers.DeviceMonitorWorker do
         "alerts:org:#{device.organization_id}:new",
         {:new_alert, device.id, :device_down}
       )
+    end
   end
 
   defp get_down_alert_message(device) do
diff --git a/lib/towerops/workers/weather_sync_worker.ex b/lib/towerops/workers/weather_sync_worker.ex
new file mode 100644
index 00000000..783f7abe
--- /dev/null
+++ b/lib/towerops/workers/weather_sync_worker.ex
@@ -0,0 +1,67 @@
+defmodule Towerops.Workers.WeatherSyncWorker do
+  @moduledoc """
+  Oban worker that periodically fetches weather data for all sites with coordinates.
+
+  Runs every 15 minutes. Batches API calls with a small delay between each
+  to stay well within OpenWeatherMap's free tier (60 calls/min).
+
+  Also cleans up observations older than 30 days on each run.
+  """
+  use Oban.Worker,
+    queue: :weather,
+    unique: [period: 600, states: [:available, :scheduled, :executing]]
+
+  alias Towerops.Sites
+  alias Towerops.Weather
+
+  require Logger
+
+  @impl Oban.Worker
+  def perform(%Oban.Job{}) do
+    api_key = Application.get_env(:towerops, :openweathermap_api_key)
+
+    if is_nil(api_key) or api_key == "" do
+      Logger.debug("Weather sync skipped: no OpenWeatherMap API key configured")
+      :ok
+    else
+      sync_all_sites()
+      Weather.cleanup_old_observations(30)
+      schedule_next()
+      :ok
+    end
+  end
+
+  defp sync_all_sites do
+    sites = Sites.list_sites_with_coordinates()
+    total = length(sites)
+
+    if total > 0 do
+      Logger.info("Weather sync: fetching weather for #{total} sites")
+
+      results =
+        sites
+        |> Enum.with_index(1)
+        |> Enum.map(fn {site, idx} ->
+          # Throttle: ~1 req/sec to stay under 60/min limit
+          if idx > 1, do: Process.sleep(1_100)
+
+          case Weather.fetch_and_store(site) do
+            {:ok, _obs} ->
+              :ok
+
+            {:error, reason} ->
+              Logger.warning("Weather fetch failed for site #{site.name}: #{inspect(reason)}")
+              :error
+          end
+        end)
+
+      ok_count = Enum.count(results, &(&1 == :ok))
+      Logger.info("Weather sync complete: #{ok_count}/#{total} sites updated")
+    end
+  end
+
+  defp schedule_next do
+    # Schedule next run in 15 minutes
+    %{} |> new(schedule_in: 900) |> Oban.insert()
+  end
+end
diff --git a/priv/repo/migrations/20260216155500_create_maintenance_windows.exs b/priv/repo/migrations/20260216155500_create_maintenance_windows.exs
new file mode 100644
index 00000000..d6939d28
--- /dev/null
+++ b/priv/repo/migrations/20260216155500_create_maintenance_windows.exs
@@ -0,0 +1,30 @@
+defmodule Towerops.Repo.Migrations.CreateMaintenanceWindows do
+  use Ecto.Migration
+
+  def change do
+    create table(:maintenance_windows, primary_key: false) do
+      add :id, :binary_id, primary_key: true
+      add :organization_id, references(:organizations, type: :binary_id, on_delete: :delete_all), null: false
+      add :site_id, references(:sites, type: :binary_id, on_delete: :delete_all)
+      add :device_id, references(:devices, type: :binary_id, on_delete: :delete_all)
+      add :name, :string, null: false
+      add :reason, :string
+      add :starts_at, :utc_datetime, null: false
+      add :ends_at, :utc_datetime, null: false
+      add :created_by_id, references(:users, type: :binary_id, on_delete: :nilify_all), null: false
+      add :recurring, :boolean, default: false
+      add :recurrence_rule, :string
+      add :suppress_alerts, :boolean, default: true
+
+      timestamps()
+    end
+
+    create index(:maintenance_windows, [:organization_id])
+    create index(:maintenance_windows, [:site_id])
+    create index(:maintenance_windows, [:device_id])
+    create index(:maintenance_windows, [:starts_at])
+    create index(:maintenance_windows, [:ends_at])
+
+    create constraint(:maintenance_windows, :ends_at_after_starts_at, check: "ends_at > starts_at")
+  end
+end
diff --git a/priv/repo/migrations/20260216155538_create_weather_observations.exs b/priv/repo/migrations/20260216155538_create_weather_observations.exs
new file mode 100644
index 00000000..cd7bb527
--- /dev/null
+++ b/priv/repo/migrations/20260216155538_create_weather_observations.exs
@@ -0,0 +1,58 @@
+defmodule Towerops.Repo.Migrations.CreateWeatherObservations do
+  use Ecto.Migration
+
+  def change do
+    create table(:weather_observations, primary_key: false) do
+      add :id, :binary_id, primary_key: true
+      add :site_id, references(:sites, type: :binary_id, on_delete: :delete_all), null: false
+
+      # Current conditions
+      add :condition, :string
+      add :condition_detail, :string
+      add :icon, :string
+      add :temperature_c, :float
+      add :feels_like_c, :float
+      add :humidity, :integer
+      add :pressure_hpa, :integer
+      add :visibility_m, :integer
+
+      # Wind
+      add :wind_speed_ms, :float
+      add :wind_gust_ms, :float
+      add :wind_deg, :integer
+
+      # Precipitation
+      add :rain_1h_mm, :float
+      add :snow_1h_mm, :float
+      add :clouds_pct, :integer
+
+      # Raw API response for future use
+      add :raw, :map
+
+      add :observed_at, :utc_datetime, null: false
+      timestamps(type: :utc_datetime)
+    end
+
+    create index(:weather_observations, [:site_id])
+    create index(:weather_observations, [:site_id, :observed_at])
+    create index(:weather_observations, [:observed_at])
+
+    # Weather alerts (severe weather warnings)
+    create table(:weather_alerts, primary_key: false) do
+      add :id, :binary_id, primary_key: true
+      add :site_id, references(:sites, type: :binary_id, on_delete: :delete_all), null: false
+      add :event, :string, null: false
+      add :sender, :string
+      add :description, :text
+      add :starts_at, :utc_datetime
+      add :ends_at, :utc_datetime
+      add :tags, {:array, :string}, default: []
+      add :severity, :string
+
+      timestamps(type: :utc_datetime)
+    end
+
+    create index(:weather_alerts, [:site_id])
+    create index(:weather_alerts, [:site_id, :ends_at])
+  end
+end