diff --git a/lib/microwaveprop/weather.ex b/lib/microwaveprop/weather.ex
index bb11d778..45e029b7 100644
--- a/lib/microwaveprop/weather.ex
+++ b/lib/microwaveprop/weather.ex
@@ -8,6 +8,7 @@ defmodule Microwaveprop.Weather do
   alias Microwaveprop.Weather.HrrrProfile
   alias Microwaveprop.Weather.IemClient
   alias Microwaveprop.Weather.IemreObservation
+  alias Microwaveprop.Weather.Metar5minObservation
   alias Microwaveprop.Weather.RtmaObservation
   alias Microwaveprop.Weather.SolarIndex
   alias Microwaveprop.Weather.Sounding
@@ -701,4 +702,50 @@ defmodule Microwaveprop.Weather do
     |> Enum.map(fn {lat, lon} -> find_nearest_iemre(lat, lon, contact.qso_timestamp) end)
     |> Enum.reject(&is_nil/1)
   end
+
+  @doc """
+  Find the nearest surface observation to a given (lat, lon, time),
+  preferring 5-minute METAR data when available, falling back to the
+  hourly `surface_observations` table.
+
+  Returns a map with `:temp_f`, `:dewpoint_f`, `:wind_speed_kts`,
+  `:observed_at`, etc. — the same shape regardless of which table the
+  data came from. Returns `nil` if neither source has data.
+  """
+  def recent_surface_obs(lat, lon, timestamp) do
+    dlat = 0.5
+    dlon = 0.5
+    time_start = DateTime.add(timestamp, -1800, :second)
+    time_end = DateTime.add(timestamp, 1800, :second)
+
+    station_ids =
+      Station
+      |> where(
+        [s],
+        s.lat >= ^(lat - dlat) and s.lat <= ^(lat + dlat) and
+          s.lon >= ^(lon - dlon) and s.lon <= ^(lon + dlon)
+      )
+      |> select([s], s.id)
+
+    # Try 5-min first
+    metar_5min =
+      Metar5minObservation
+      |> where([o], o.station_id in subquery(station_ids))
+      |> where([o], o.observed_at >= ^time_start and o.observed_at <= ^time_end)
+      |> order_by([o], asc: fragment("ABS(EXTRACT(EPOCH FROM ? - ?))", o.observed_at, ^timestamp))
+      |> limit(1)
+      |> Repo.one()
+
+    if metar_5min do
+      metar_5min
+    else
+      # Fall back to hourly
+      SurfaceObservation
+      |> where([o], o.station_id in subquery(station_ids))
+      |> where([o], o.observed_at >= ^time_start and o.observed_at <= ^time_end)
+      |> order_by([o], asc: fragment("ABS(EXTRACT(EPOCH FROM ? - ?))", o.observed_at, ^timestamp))
+      |> limit(1)
+      |> Repo.one()
+    end
+  end
 end
diff --git a/lib/microwaveprop/weather/metar_5min_observation.ex b/lib/microwaveprop/weather/metar_5min_observation.ex
new file mode 100644
index 00000000..bc860978
--- /dev/null
+++ b/lib/microwaveprop/weather/metar_5min_observation.ex
@@ -0,0 +1,43 @@
+defmodule Microwaveprop.Weather.Metar5minObservation do
+  @moduledoc """
+  5-minute ASOS/METAR observations from NCEI (C00418).
+
+  Schema-identical to `SurfaceObservation` but stored in a separate
+  table to avoid mixing cadences and preserve backward compatibility
+  for existing queries against the hourly feed.
+  """
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  @primary_key {:id, :binary_id, autogenerate: true}
+  @foreign_key_type :binary_id
+
+  schema "metar_5min_observations" do
+    belongs_to :station, Microwaveprop.Weather.Station
+    field :observed_at, :utc_datetime
+    field :temp_f, :float
+    field :dewpoint_f, :float
+    field :relative_humidity, :float
+    field :wind_speed_kts, :float
+    field :wind_direction_deg, :integer
+    field :sea_level_pressure_mb, :float
+    field :altimeter_setting, :float
+    field :sky_condition, :string
+    field :precip_1h_in, :float
+    field :wx_codes, :string
+
+    timestamps(type: :utc_datetime)
+  end
+
+  @required_fields ~w(station_id observed_at)a
+  @optional_fields ~w(temp_f dewpoint_f relative_humidity wind_speed_kts wind_direction_deg sea_level_pressure_mb altimeter_setting sky_condition precip_1h_in wx_codes)a
+
+  def changeset(observation, attrs) do
+    observation
+    |> cast(attrs, @required_fields ++ @optional_fields)
+    |> validate_required(@required_fields)
+    |> foreign_key_constraint(:station_id)
+    |> unique_constraint([:station_id, :observed_at])
+  end
+end
diff --git a/lib/microwaveprop/weather/ncei_metar_client.ex b/lib/microwaveprop/weather/ncei_metar_client.ex
new file mode 100644
index 00000000..150e8fda
--- /dev/null
+++ b/lib/microwaveprop/weather/ncei_metar_client.ex
@@ -0,0 +1,191 @@
+defmodule Microwaveprop.Weather.NceiMetarClient do
+  @moduledoc """
+  Fetches 5-minute ASOS observations from NCEI's C00418 dataset.
+
+  Data URL pattern:
+  ```
+  https://www.ncei.noaa.gov/data/automated-surface-observing-system-five-minute/access/YYYY/MM/asos-5min-KXXX-YYYYMM.dat
+  ```
+
+  Each file is one station-month of 5-minute observations in a
+  fixed-width METAR-like format. See the meteorologist's recommendation
+  in the April 2026 review.
+  """
+
+  require Logger
+
+  @base_url "https://www.ncei.noaa.gov/data/automated-surface-observing-system-five-minute/access"
+
+  @doc """
+  Fetch and parse 5-minute observations for a given station, year, and month.
+
+  Returns `{:ok, [parsed_obs]}` or `{:error, reason}`.
+  """
+  def fetch(icao, year, month) do
+    month_str = month |> Integer.to_string() |> String.pad_leading(2, "0")
+    url = "#{@base_url}/#{year}/#{month_str}/asos-5min-#{icao}-#{year}#{month_str}.dat"
+
+    case Req.get(url, receive_timeout: 60_000) do
+      {:ok, %{status: 200, body: body}} ->
+        {:ok, parse(body)}
+
+      {:ok, %{status: status}} ->
+        {:error, "NCEI 5-min HTTP #{status}"}
+
+      {:error, reason} ->
+        {:error, reason}
+    end
+  end
+
+  @doc """
+  Parse the fixed-width NCEI 5-minute ASOS format into maps.
+
+  Each line has a METAR embedded in a fixed-width wrapper. We extract
+  the key fields without a full METAR parser — this covers the data
+  the scorer and backtest need (temp, dewpoint, wind, pressure, sky).
+  """
+  def parse(text) when is_binary(text) do
+    text
+    |> String.split("\n")
+    |> Enum.flat_map(&parse_line/1)
+  end
+
+  defp parse_line(line) when byte_size(line) < 60, do: []
+
+  defp parse_line(line) do
+    # Fixed-width header: WBAN(5) ICAO(4) FAA(4) DATE(8) HHMM(4) ...
+    # Then METAR text after the "5-MIN" marker
+    with <<_wban::binary-5, icao::binary-4, _faa::binary-4, date::binary-8, hhmm::binary-4, _rest::binary>> <- line,
+         {:ok, observed_at} <- parse_datetime(date, hhmm),
+         metar_text <- extract_metar(line) do
+      obs = parse_metar_fields(metar_text)
+      [Map.merge(obs, %{icao: String.trim(icao), observed_at: observed_at})]
+    else
+      _ -> []
+    end
+  end
+
+  defp parse_datetime(<<y::binary-4, m::binary-2, d::binary-2>>, <<hh::binary-2, mm::binary-2>>) do
+    with {year, ""} <- Integer.parse(y),
+         {month, ""} <- Integer.parse(m),
+         {day, ""} <- Integer.parse(d),
+         {hour, ""} <- Integer.parse(hh),
+         {minute, ""} <- Integer.parse(mm),
+         {:ok, date} <- Date.new(year, month, day),
+         {:ok, time} <- Time.new(hour, minute, 0),
+         {:ok, dt} <- DateTime.new(date, time, "Etc/UTC") do
+      {:ok, DateTime.truncate(dt, :second)}
+    else
+      _ -> :error
+    end
+  end
+
+  defp extract_metar(line) do
+    case String.split(line, "5-MIN ", parts: 2) do
+      [_, metar] -> metar
+      _ -> ""
+    end
+  end
+
+  defp parse_metar_fields(metar) do
+    parts = String.split(metar)
+
+    %{
+      temp_f: extract_temp_f(parts),
+      dewpoint_f: extract_dewpoint_f(parts),
+      wind_speed_kts: extract_wind_speed(parts),
+      wind_direction_deg: extract_wind_dir(parts),
+      altimeter_setting: extract_altimeter(parts),
+      sky_condition: extract_sky(parts),
+      relative_humidity: nil,
+      sea_level_pressure_mb: nil,
+      precip_1h_in: nil,
+      wx_codes: nil
+    }
+  end
+
+  # Extract precise temp/dew from RMK T-group: T02110094 → 21.1°C / 9.4°C
+  defp extract_temp_f(parts) do
+    with t_group when is_binary(t_group) <- Enum.find(parts, &String.starts_with?(&1, "T0")) do
+      parse_t_group_temp(t_group)
+    else
+      _ ->
+        # Fall back to temp/dew field: "21/09"
+        with td when is_binary(td) <- Enum.find(parts, &Regex.match?(~r/^M?\d+\/M?\d+$/, &1)) do
+          [t, _d] = String.split(td, "/")
+          parse_metar_temp(t) |> c_to_f()
+        else
+          _ -> nil
+        end
+    end
+  end
+
+  defp extract_dewpoint_f(parts) do
+    with t_group when is_binary(t_group) <- Enum.find(parts, &String.starts_with?(&1, "T0")) do
+      parse_t_group_dew(t_group)
+    else
+      _ ->
+        with td when is_binary(td) <- Enum.find(parts, &Regex.match?(~r/^M?\d+\/M?\d+$/, &1)) do
+          [_t, d] = String.split(td, "/")
+          parse_metar_temp(d) |> c_to_f()
+        else
+          _ -> nil
+        end
+    end
+  end
+
+  # T02110094 → temp = +21.1°C, dew = +9.4°C (leading 0=+, 1=-)
+  defp parse_t_group_temp(<<"T", sign::binary-1, d1::binary-2, d2::binary-1, _rest::binary>>) do
+    val = String.to_integer(d1) + String.to_integer(d2) / 10.0
+    (if sign == "1", do: -val, else: val) |> c_to_f()
+  end
+
+  defp parse_t_group_temp(_), do: nil
+
+  defp parse_t_group_dew(<<"T", _::binary-4, sign::binary-1, d1::binary-2, d2::binary-1, _rest::binary>>) do
+    val = String.to_integer(d1) + String.to_integer(d2) / 10.0
+    (if sign == "1", do: -val, else: val) |> c_to_f()
+  end
+
+  defp parse_t_group_dew(_), do: nil
+
+  defp parse_metar_temp("M" <> rest), do: -String.to_integer(rest) * 1.0
+  defp parse_metar_temp(s), do: String.to_integer(s) * 1.0
+
+  defp c_to_f(c) when is_number(c), do: c * 9.0 / 5.0 + 32.0
+  defp c_to_f(_), do: nil
+
+  defp extract_wind_speed(parts) do
+    with wind when is_binary(wind) <- Enum.find(parts, &Regex.match?(~r/^\d{3}\d{2,3}KT/, &1)),
+         {speed, _} <- Integer.parse(String.slice(wind, 3..4)) do
+      speed * 1.0
+    else
+      _ -> nil
+    end
+  end
+
+  defp extract_wind_dir(parts) do
+    with wind when is_binary(wind) <- Enum.find(parts, &Regex.match?(~r/^\d{3}\d{2,3}KT/, &1)),
+         {dir, _} <- Integer.parse(String.slice(wind, 0..2)) do
+      dir
+    else
+      _ -> nil
+    end
+  end
+
+  defp extract_altimeter(parts) do
+    with alt when is_binary(alt) <- Enum.find(parts, &String.starts_with?(&1, "A2")) do
+      case Float.parse(String.slice(alt, 1..-1//1)) do
+        {val, _} -> val / 100.0
+        :error -> nil
+      end
+    else
+      _ -> nil
+    end
+  end
+
+  defp extract_sky(parts) do
+    sky_tokens = Enum.filter(parts, &Regex.match?(~r/^(CLR|FEW|SCT|BKN|OVC|VV)\d*/, &1))
+    if sky_tokens != [], do: Enum.join(sky_tokens, " "), else: nil
+  end
+end
diff --git a/priv/repo/migrations/20260410134951_create_metar_5min_observations.exs b/priv/repo/migrations/20260410134951_create_metar_5min_observations.exs
new file mode 100644
index 00000000..aa3e927a
--- /dev/null
+++ b/priv/repo/migrations/20260410134951_create_metar_5min_observations.exs
@@ -0,0 +1,26 @@
+defmodule Microwaveprop.Repo.Migrations.CreateMetar5minObservations do
+  use Ecto.Migration
+
+  def change do
+    create table(:metar_5min_observations, primary_key: false) do
+      add :id, :binary_id, primary_key: true, null: false
+      add :station_id, references(:weather_stations, type: :binary_id, on_delete: :delete_all)
+      add :observed_at, :utc_datetime, null: false
+      add :temp_f, :float
+      add :dewpoint_f, :float
+      add :relative_humidity, :float
+      add :wind_speed_kts, :float
+      add :wind_direction_deg, :integer
+      add :sea_level_pressure_mb, :float
+      add :altimeter_setting, :float
+      add :sky_condition, :string
+      add :precip_1h_in, :float
+      add :wx_codes, :string
+
+      timestamps(type: :utc_datetime)
+    end
+
+    create unique_index(:metar_5min_observations, [:station_id, :observed_at])
+    create index(:metar_5min_observations, [:observed_at])
+  end
+end
diff --git a/test/microwaveprop/weather/ncei_metar_client_test.exs b/test/microwaveprop/weather/ncei_metar_client_test.exs
new file mode 100644
index 00000000..970d6765
--- /dev/null
+++ b/test/microwaveprop/weather/ncei_metar_client_test.exs
@@ -0,0 +1,49 @@
+defmodule Microwaveprop.Weather.NceiMetarClientTest do
+  use ExUnit.Case, async: true
+
+  alias Microwaveprop.Weather.NceiMetarClient
+
+  @sample_line "03927KDFW DFW20260301000010303/01/26 00:00:31  5-MIN KDFW 010600Z 17012KT 10SM CLR 21/09 A2997 560 47 1400 160/12 RMK AO2 T02110094"
+
+  describe "parse/1" do
+    test "parses a single KDFW observation" do
+      [obs] = NceiMetarClient.parse(@sample_line)
+
+      assert obs.icao == "KDFW"
+      assert obs.observed_at == ~U[2026-03-01 00:00:00Z]
+      # T02110094 → 21.1°C = 70.0°F, 9.4°C = 48.9°F
+      assert_in_delta obs.temp_f, 70.0, 0.2
+      assert_in_delta obs.dewpoint_f, 48.9, 0.2
+      assert obs.wind_speed_kts == 12.0
+      assert obs.wind_direction_deg == 170
+      assert_in_delta obs.altimeter_setting, 29.97, 0.01
+      assert obs.sky_condition == "CLR"
+    end
+
+    test "parses multiple lines" do
+      text = """
+      03927KDFW DFW20260301000010303/01/26 00:00:31  5-MIN KDFW 010600Z 17012KT 10SM CLR 21/09 A2997 560 47 1400 160/12 RMK AO2 T02110094
+      03927KDFW DFW20260301000510303/01/26 00:05:31  5-MIN KDFW 010605Z 17012KT 10SM CLR 21/09 A2997 560 47 1400 160/12 RMK AO2 T02110094
+      """
+
+      obs = NceiMetarClient.parse(text)
+      assert length(obs) == 2
+      assert Enum.at(obs, 0).observed_at == ~U[2026-03-01 00:00:00Z]
+      assert Enum.at(obs, 1).observed_at == ~U[2026-03-01 00:05:00Z]
+    end
+
+    test "skips blank or too-short lines" do
+      assert NceiMetarClient.parse("") == []
+      assert NceiMetarClient.parse("short\n\n") == []
+    end
+
+    test "handles negative temperatures via M prefix" do
+      line = "03927KDFW DFW20260115120010103/15/26 12:00:31  5-MIN KDFW 151200Z 36005KT 10SM CLR M02/M08 A3032 560 47 1400 360/05 RMK AO2"
+      [obs] = NceiMetarClient.parse(line)
+
+      # M02 = -2°C = 28.4°F, M08 = -8°C = 17.6°F
+      assert_in_delta obs.temp_f, 28.4, 0.2
+      assert_in_delta obs.dewpoint_f, 17.6, 0.2
+    end
+  end
+end