diff --git a/algo.md b/algo.md
index 05a2d395..0728c6fb 100644
--- a/algo.md
+++ b/algo.md
@@ -1153,18 +1153,19 @@ Revised April 2026 based on 57,248 QSO-HRRR correlation analysis. Key changes fr
 | Wind | 6% | 5% | Minimal impact confirmed |
 
 ```elixir
+# Recalibrated 2026-04-11 via gradient descent on 5000 QSOs (loss 0.42 → 0.12)
 def composite_score(factors) do
   round(
-    factors.humidity      * 0.18 +
-    factors.pressure      * 0.15 +
-    factors.time_of_day   * 0.10 +
-    factors.td_depression * 0.10 +
-    factors.pwat          * 0.10 +
-    factors.refractivity  * 0.08 +
+    factors.rain          * 0.1362 +
+    factors.humidity      * 0.1243 +
+    factors.pwat          * 0.1128 +
+    factors.season        * 0.1112 +
+    factors.refractivity  * 0.1049 +
+    factors.pressure      * 0.1032 +
+    factors.td_depression * 0.0978 +
     factors.sky           * 0.08 +
-    factors.season        * 0.08 +
-    factors.rain          * 0.08 +
-    factors.wind          * 0.05
+    factors.wind          * 0.08 +
+    factors.time_of_day   * 0.0496
   )
 end
 ```
diff --git a/lib/microwaveprop/propagation/band_config.ex b/lib/microwaveprop/propagation/band_config.ex
index 850487fd..eac3926b 100644
--- a/lib/microwaveprop/propagation/band_config.ex
+++ b/lib/microwaveprop/propagation/band_config.ex
@@ -7,17 +7,19 @@ defmodule Microwaveprop.Propagation.BandConfig do
   algorithm is tuned or new bands are added, only this module changes.
   """
 
+  # Recalibrated 2026-04-11 via gradient descent on 5000 QSOs (loss 0.42 → 0.12).
+  # Key shifts: rain +70%, season +39%, wind +60%; time_of_day -50%, pressure -31%.
   @weights %{
-    humidity: 0.18,
-    time_of_day: 0.10,
-    td_depression: 0.10,
-    refractivity: 0.08,
+    humidity: 0.1243,
+    time_of_day: 0.0496,
+    td_depression: 0.0978,
+    refractivity: 0.1049,
     sky: 0.08,
-    season: 0.08,
-    wind: 0.05,
-    rain: 0.08,
-    pressure: 0.15,
-    pwat: 0.10
+    season: 0.1112,
+    wind: 0.08,
+    rain: 0.1362,
+    pressure: 0.1032,
+    pwat: 0.1128
   }
 
   @sunrise_table [7.4, 7.3, 7.0, 6.7, 6.35, 6.25, 6.35, 6.65, 6.9, 7.1, 7.35, 7.45]
diff --git a/test/microwaveprop/propagation/band_config_test.exs b/test/microwaveprop/propagation/band_config_test.exs
index c9911b40..5082589b 100644
--- a/test/microwaveprop/propagation/band_config_test.exs
+++ b/test/microwaveprop/propagation/band_config_test.exs
@@ -143,16 +143,16 @@ defmodule Microwaveprop.Propagation.BandConfigTest do
 
     test "individual weights have correct values" do
       weights = BandConfig.weights()
-      assert weights.humidity == 0.18
-      assert weights.time_of_day == 0.10
-      assert weights.td_depression == 0.10
-      assert weights.refractivity == 0.08
+      assert weights.humidity == 0.1243
+      assert weights.time_of_day == 0.0496
+      assert weights.td_depression == 0.0978
+      assert weights.refractivity == 0.1049
       assert weights.sky == 0.08
-      assert weights.season == 0.08
-      assert weights.wind == 0.05
-      assert weights.rain == 0.08
-      assert weights.pwat == 0.10
-      assert weights.pressure == 0.15
+      assert weights.season == 0.1112
+      assert weights.wind == 0.08
+      assert weights.rain == 0.1362
+      assert weights.pwat == 0.1128
+      assert weights.pressure == 0.1032
     end
   end