diff --git a/lib/microwaveprop/weather.ex b/lib/microwaveprop/weather.ex
index a400b1f1..d9a032b6 100644
--- a/lib/microwaveprop/weather.ex
+++ b/lib/microwaveprop/weather.ex
@@ -263,6 +263,9 @@ defmodule Microwaveprop.Weather do
   """
   def prune_old_grid_profiles do
     cutoff = DateTime.add(DateTime.utc_now(), -24, :hour)
+    # Bound the scan to recent partitions only (grid profiles are at most ~48h old).
+    # Without a lower bound, Postgres scans every partition back to 2016.
+    floor = DateTime.add(DateTime.utc_now(), -72, :hour)
 
     # Only delete profiles on the 0.125° propagation grid, preserving QSO-linked
     # profiles which sit at arbitrary lat/lon positions (HRRR's native ~3km grid).
@@ -270,12 +273,12 @@ defmodule Microwaveprop.Weather do
       Repo.query!(
         """
         DELETE FROM hrrr_profiles
-        WHERE valid_time < $1
+        WHERE valid_time >= $2 AND valid_time < $1
           AND (lat * 1000)::int % 125 = 0
           AND (lon * 1000)::int % 125 = 0
         """,
-        [cutoff],
-        timeout: 120_000
+        [cutoff, floor],
+        timeout: 300_000
       )
 
     if deleted > 0 do