diff --git a/assets/js/weather_map_hook.ts b/assets/js/weather_map_hook.ts
index c1268d77..9a93e103 100644
--- a/assets/js/weather_map_hook.ts
+++ b/assets/js/weather_map_hook.ts
@@ -1142,7 +1142,18 @@ export const WeatherMap: WeatherMapHook = {
 
     try {
       const resp = await fetch(url, { signal: abort.signal })
-      if (!resp.ok) return
+      if (!resp.ok) {
+        // Never swallow a failed tile fetch. A 413 (viewport too large —
+        // reachable by zooming to minZoom on a wide window) or a 400
+        // leaves the map blank with no other signal, which is
+        // indistinguishable from "no data for this hour" when someone
+        // reports a missing overlay.
+        console.warn(
+          `weather cells fetch failed (${source}): HTTP ${resp.status}`,
+          { status: resp.status, layers, url }
+        )
+        return
+      }
       const buf = await resp.arrayBuffer()
       if (cacheKey !== this.packKey) return