feat: NWS high/low temperature pairing in forecasts

src/accessiweather/weather_client_nws.py

@@ -1168,7 +1168,9 @@ def parse_nws_forecast(data: dict) -> Forecast:
     """Parse NWS forecast payload into a Forecast model."""
     periods = []
 
-    for period_data in data.get("properties", {}).get("periods", []):
+    raw_periods = data.get("properties", {}).get("periods", [])
+
+    for period_data in raw_periods:
         temperature, temperature_unit = _extract_temperature(
             period_data.get("temperature"), period_data.get("temperatureUnit")
         )
@@ -1205,6 +1207,19 @@ def parse_nws_forecast(data: dict) -> Forecast:
         )
         periods.append(period)
 
+    # Pair daytime/nighttime periods to populate high/low temperatures.
+    # NWS returns alternating day/night periods (isDaytime flag). Set the
+    # nighttime temperature as temperature_low on the preceding daytime period.
+    for i, period_data in enumerate(raw_periods):
+        if period_data.get("isDaytime") and i + 1 < len(raw_periods):
+            next_data = raw_periods[i + 1]
+            if not next_data.get("isDaytime"):
+                night_temp, _ = _extract_temperature(
+                    next_data.get("temperature"), next_data.get("temperatureUnit")
+                )
+                if night_temp is not None:
+                    periods[i].temperature_low = night_temp
+
     return Forecast(periods=periods, generated_at=datetime.now())
 
 

tests/test_nws_high_low.py

@@ -0,0 +1,85 @@
+"""Tests for NWS high/low temperature pairing in parse_nws_forecast."""
+
+from accessiweather.weather_client_nws import parse_nws_forecast
+
+
+def _make_period(name, temp, unit="F", is_daytime=True):
+    return {
+        "name": name,
+        "temperature": temp,
+        "temperatureUnit": unit,
+        "isDaytime": is_daytime,
+        "shortForecast": "Sunny",
+        "detailedForecast": "",
+        "windSpeed": "10 mph",
+        "windDirection": "N",
+        "icon": "",
+        "startTime": "2026-02-12T06:00:00-05:00",
+        "endTime": "2026-02-12T18:00:00-05:00",
+    }
+
+
+def _wrap(periods):
+    return {"properties": {"periods": periods}}
+
+
+class TestNwsHighLowPairing:
+    def test_daytime_gets_nighttime_low(self):
+        data = _wrap(
+            [
+                _make_period("Today", 34, is_daytime=True),
+                _make_period("Tonight", 16, is_daytime=False),
+            ]
+        )
+        forecast = parse_nws_forecast(data)
+        assert forecast.periods[0].temperature == 34
+        assert forecast.periods[0].temperature_low == 16
+        assert forecast.periods[1].temperature == 16
+        assert forecast.periods[1].temperature_low is None
+
+    def test_multiple_day_night_pairs(self):
+        data = _wrap(
+            [
+                _make_period("Today", 34, is_daytime=True),
+                _make_period("Tonight", 16, is_daytime=False),
+                _make_period("Friday", 36, is_daytime=True),
+                _make_period("Friday Night", 20, is_daytime=False),
+            ]
+        )
+        forecast = parse_nws_forecast(data)
+        assert forecast.periods[0].temperature_low == 16
+        assert forecast.periods[2].temperature_low == 20
+
+    def test_nighttime_first_no_crash(self):
+        """When forecast starts at night (evening request), no pairing for first period."""
+        data = _wrap(
+            [
+                _make_period("Tonight", 16, is_daytime=False),
+                _make_period("Friday", 36, is_daytime=True),
+                _make_period("Friday Night", 20, is_daytime=False),
+            ]
+        )
+        forecast = parse_nws_forecast(data)
+        assert forecast.periods[0].temperature_low is None
+        assert forecast.periods[1].temperature_low == 20
+
+    def test_single_daytime_period_no_crash(self):
+        data = _wrap([_make_period("Today", 34, is_daytime=True)])
+        forecast = parse_nws_forecast(data)
+        assert forecast.periods[0].temperature_low is None
+
+    def test_empty_periods(self):
+        forecast = parse_nws_forecast({"properties": {"periods": []}})
+        assert len(forecast.periods) == 0
+
+    def test_consecutive_daytime_no_pairing(self):
+        """Two daytime periods in a row shouldn't pair."""
+        data = _wrap(
+            [
+                _make_period("Today", 34, is_daytime=True),
+                _make_period("Tomorrow", 36, is_daytime=True),
+            ]
+        )
+        forecast = parse_nws_forecast(data)
+        assert forecast.periods[0].temperature_low is None
+        assert forecast.periods[1].temperature_low is None