diff --git a/config/dev.exs b/config/dev.exs
index ff6b67fa..0bf69a28 100644
--- a/config/dev.exs
+++ b/config/dev.exs
@@ -92,6 +92,9 @@ config :microwaveprop, load_ml_model: true
 # Use local SRTM1 tiles for elevation lookups instead of the Open-Meteo API
 config :microwaveprop, srtm_tiles_dir: Path.expand("~/srtm/tiles")
 
+# Cache raw HRRR GRIB2 files locally (dev only — do not delete)
+config :microwaveprop, hrrr_cache_dir: Path.expand("~/hrrr")
+
 # Freshness monitor watches for stale propagation scores
 config :microwaveprop, start_freshness_monitor: true
 
diff --git a/lib/microwaveprop/weather/hrrr_client.ex b/lib/microwaveprop/weather/hrrr_client.ex
index 46fd6155..606e065e 100644
--- a/lib/microwaveprop/weather/hrrr_client.ex
+++ b/lib/microwaveprop/weather/hrrr_client.ex
@@ -298,6 +298,27 @@ defmodule Microwaveprop.Weather.HrrrClient do
   defp download_grib_ranges(_url, []), do: {:ok, <<>>}
 
   defp download_grib_ranges(url, ranges) do
+    # Check local cache first (dev only)
+    cache_key = url_to_cache_key(url, ranges)
+
+    case read_cache(cache_key) do
+      {:ok, binary} ->
+        Logger.info("HRRR cache hit: #{cache_key}")
+        {:ok, binary}
+
+      :miss ->
+        case download_grib_ranges_remote(url, ranges) do
+          {:ok, binary} = ok ->
+            write_cache(cache_key, binary)
+            ok
+
+          error ->
+            error
+        end
+    end
+  end
+
+  defp download_grib_ranges_remote(url, ranges) do
     # Merge adjacent/overlapping ranges to reduce HTTP requests
     merged = merge_ranges(ranges)
 
@@ -336,6 +357,39 @@ defmodule Microwaveprop.Weather.HrrrClient do
     end
   end
 
+  defp hrrr_cache_dir, do: Application.get_env(:microwaveprop, :hrrr_cache_dir)
+
+  defp url_to_cache_key(url, ranges) do
+    # e.g. hrrr.20240922_conus_hrrr.t18z.wrfprsf00_r42.grib2
+    uri = URI.parse(url)
+    path_part = uri.path |> String.trim_leading("/") |> String.replace("/", "_")
+    range_hash = ranges |> :erlang.phash2() |> Integer.to_string(16)
+    "#{path_part}_r#{range_hash}.grib2"
+  end
+
+  defp read_cache(key) do
+    case hrrr_cache_dir() do
+      nil -> :miss
+      dir ->
+        path = Path.join(dir, key)
+        case File.read(path) do
+          {:ok, binary} -> {:ok, binary}
+          {:error, _} -> :miss
+        end
+    end
+  end
+
+  defp write_cache(key, binary) do
+    case hrrr_cache_dir() do
+      nil -> :ok
+      dir ->
+        File.mkdir_p!(dir)
+        path = Path.join(dir, key)
+        File.write!(path, binary)
+        Logger.info("HRRR cached: #{path} (#{byte_size(binary)} bytes)")
+    end
+  end
+
   defp merge_ranges(ranges) do
     ranges
     |> Enum.sort_by(&elem(&1, 0))
diff --git a/lib/mix/tasks/hrrr_backfill.ex b/lib/mix/tasks/hrrr_backfill.ex
new file mode 100644
index 00000000..04c9dbc9
--- /dev/null
+++ b/lib/mix/tasks/hrrr_backfill.ex
@@ -0,0 +1,149 @@
+defmodule Mix.Tasks.HrrrBackfill do
+  @moduledoc """
+  Re-fetches HRRR profiles for all QSO-linked contacts with the current
+  (finer) pressure level set. Replaces existing profiles with updated data.
+
+  Usage:
+      mix hrrr_backfill              # backfill all contacts missing HRRR or with < 13 levels
+      mix hrrr_backfill --all        # re-fetch all contacts regardless of level count
+      mix hrrr_backfill --limit 100  # process at most 100 hours
+  """
+
+  use Mix.Task
+
+  import Ecto.Query
+
+  alias Microwaveprop.Radio
+  alias Microwaveprop.Radio.Contact
+  alias Microwaveprop.Repo
+  alias Microwaveprop.Weather
+  alias Microwaveprop.Weather.HrrrClient
+  alias Microwaveprop.Weather.HrrrProfile
+  alias Microwaveprop.Weather.SoundingParams
+
+  require Logger
+
+  @min_levels 13
+
+  @impl Mix.Task
+  def run(args) do
+    Mix.Task.run("app.start")
+
+    {opts, _, _} = OptionParser.parse(args, switches: [all: :boolean, limit: :integer])
+    refetch_all? = Keyword.get(opts, :all, false)
+    limit = Keyword.get(opts, :limit, nil)
+
+    # Get all distinct (rounded_hour, path_points) combinations for contacts
+    contacts =
+      from(c in Contact,
+        where: not is_nil(c.pos1) and c.qso_timestamp >= ^~U[2014-01-01 00:00:00Z],
+        select: %{id: c.id, pos1: c.pos1, pos2: c.pos2, qso_timestamp: c.qso_timestamp},
+        order_by: [desc: c.qso_timestamp]
+      )
+      |> Repo.all()
+
+    # Group by rounded HRRR hour to batch requests
+    by_hour =
+      contacts
+      |> Enum.flat_map(fn c ->
+        hour = HrrrClient.nearest_hrrr_hour(c.qso_timestamp)
+
+        Radio.contact_path_points(c)
+        |> Enum.map(fn {lat, lon} ->
+          {rlat, rlon} = Weather.round_to_hrrr_grid(lat, lon)
+          {hour, {rlat, rlon}}
+        end)
+      end)
+      |> Enum.group_by(fn {hour, _} -> hour end, fn {_, point} -> point end)
+      |> Enum.map(fn {hour, points} -> {hour, Enum.uniq(points)} end)
+      |> Enum.sort_by(fn {hour, _} -> hour end, {:desc, DateTime})
+
+    # Filter to only hours needing backfill
+    by_hour =
+      if refetch_all? do
+        by_hour
+      else
+        Enum.filter(by_hour, fn {hour, points} ->
+          needs_backfill?(hour, points)
+        end)
+      end
+
+    by_hour = if limit, do: Enum.take(by_hour, limit), else: by_hour
+
+    total = length(by_hour)
+    total_points = Enum.reduce(by_hour, 0, fn {_, pts}, acc -> acc + length(pts) end)
+    Logger.info("HRRR backfill: #{total} hours, #{total_points} points to process")
+
+    by_hour
+    |> Enum.with_index(1)
+    |> Enum.each(fn {{hour, points}, idx} ->
+      Logger.info("HRRR backfill [#{idx}/#{total}]: #{hour} (#{length(points)} points)")
+
+      case HrrrClient.fetch_grid(points, hour) do
+        {:ok, grid_data} ->
+          Enum.each(grid_data, fn {{lat, lon}, data} ->
+            store_profile(lat, lon, hour, data)
+          end)
+
+          Logger.info("HRRR backfill [#{idx}/#{total}]: saved #{map_size(grid_data)} profiles")
+
+        {:error, reason} ->
+          Logger.warning("HRRR backfill [#{idx}/#{total}]: failed - #{inspect(reason)}")
+      end
+
+      # Rate limit to avoid overwhelming NOAA
+      if idx < total, do: Process.sleep(500)
+    end)
+
+    Logger.info("HRRR backfill complete")
+  end
+
+  defp needs_backfill?(hour, points) do
+    # Check if any point for this hour is missing or has fewer than @min_levels
+    sample = hd(points)
+    {lat, lon} = sample
+
+    case Repo.one(
+           from(h in HrrrProfile,
+             where: h.lat == ^lat and h.lon == ^lon and h.valid_time == ^hour,
+             select: fragment("array_length(profile, 1)")
+           )
+         ) do
+      nil -> true
+      count when count < @min_levels -> true
+      _ -> false
+    end
+  end
+
+  defp store_profile(lat, lon, valid_time, data) do
+    params = SoundingParams.derive(data.profile)
+
+    attrs =
+      %{
+        valid_time: valid_time,
+        lat: lat,
+        lon: lon,
+        run_time: data.run_time,
+        profile: data.profile,
+        hpbl_m: data.hpbl_m,
+        pwat_mm: data.pwat_mm,
+        surface_temp_c: data.surface_temp_c,
+        surface_dewpoint_c: data.surface_dewpoint_c,
+        surface_pressure_mb: data.surface_pressure_mb
+      }
+      |> maybe_add_derived(params)
+
+    Weather.upsert_hrrr_profile(attrs)
+  end
+
+  defp maybe_add_derived(attrs, nil), do: attrs
+
+  defp maybe_add_derived(attrs, params) do
+    Map.merge(attrs, %{
+      surface_refractivity: params.surface_refractivity,
+      min_refractivity_gradient: params.min_refractivity_gradient,
+      ducting_detected: params.ducting_detected,
+      duct_characteristics: params.duct_characteristics
+    })
+  end
+end