diff --git a/app/api/routes/weather.py b/app/api/routes/weather.py
index f1e7980..d696e87 100644
--- a/app/api/routes/weather.py
+++ b/app/api/routes/weather.py
@@ -2,6 +2,7 @@
 
 from fastapi import APIRouter, Query
 from fastapi.exceptions import RequestValidationError
+from openmeteo_requests.Client import OpenMeteoRequestsError
 
 from app.core.errors.base import AppError
 from app.services.external_apis.weather_api import WeatherAPI
@@ -55,5 +56,8 @@ def get_weather_forecast(
             latitude, longitude, start_date.isoformat(), end_date.isoformat(), hourly_fields=requested
         )
         return weather_data
+    except OpenMeteoRequestsError as e:
+        # Open-Meteo failed or was unreachable: the failure is upstream, not ours
+        raise AppError(str(e), status_code=502, error_code="WEATHER_FETCH_FAILED")
     except Exception as e:
         raise AppError(str(e), status_code=500)
\ No newline at end of file
diff --git a/tests/test_api.py b/tests/test_api.py
index 350cf0c..06af417 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -614,6 +614,29 @@ def fake_get_weather(self, latitude, longitude, start_date, end_date, hourly_fie
             "end_date": "2026-10-20",
         }
 
+    def test_forecast_upstream_error_is_502(self, client, monkeypatch):
+        from openmeteo_requests.Client import OpenMeteoRequestsError
+
+        def fake_weather_api(*args, **kwargs):
+            raise OpenMeteoRequestsError("failed to request 'https://api.open-meteo.com/v1/forecast': offline")
+
+        monkeypatch.setattr("openmeteo_requests.Client.weather_api", fake_weather_api)
+
+        resp = client.get(self.WEATHER_URL, params=self.VALID)
+        assert resp.status_code == 502
+        body = resp.json()
+        assert body["error_code"] == "WEATHER_FETCH_FAILED"
+        assert "offline" in body["message"]
+
+    def test_forecast_unexpected_error_is_500(self, client, monkeypatch):
+        def fake_get_weather(*args, **kwargs):
+            raise ValueError("boom")
+
+        monkeypatch.setattr("app.api.routes.weather.WeatherAPI.get_weather", fake_get_weather)
+
+        resp = client.get(self.WEATHER_URL, params=self.VALID)
+        assert resp.status_code == 500
+
     @pytest.mark.parametrize(
         "overrides, field",
         [