diff --git a/lib/microwaveprop/weather/hrrr_client.ex b/lib/microwaveprop/weather/hrrr_client.ex
index 35b6abd2..46fd6155 100644
--- a/lib/microwaveprop/weather/hrrr_client.ex
+++ b/lib/microwaveprop/weather/hrrr_client.ex
@@ -9,7 +9,12 @@ defmodule Microwaveprop.Weather.HrrrClient do
 
   @hrrr_base "https://noaa-hrrr-bdp-pds.s3.amazonaws.com"
 
-  @pressure_levels [1000, 975, 950, 925, 900, 850, 800, 700]
+  # Fine-grained levels below 900mb (~1km) for duct detection, plus standard upper levels.
+  # Every 25mb from 1000-900 for ~80m vertical spacing near surface.
+  @pressure_levels [
+    1000, 975, 950, 925, 900,
+    875, 850, 825, 800, 775, 750, 725, 700
+  ]
 
   @surface_messages [
     %{var: "TMP", level: "2 m above ground"},