Add OpenWeatherMap weather forecasts. Closes #48

Show 8-day Bristol home weather on the index and weekends pages.
Show destination weather per day on the trip list and trip page.
Cache forecasts in ~/lib/data/weather/ and refresh via update.py.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agenda/weather.py

@@ -0,0 +1,83 @@
+"""Weather forecast using OpenWeatherMap One Call API."""
+
+import json
+import os
+from datetime import datetime
+
+import pyowm
+
+
+def _cache_path(data_dir: str, lat: float, lon: float) -> str:
+    """Path for weather cache file."""
+    weather_dir = os.path.join(data_dir, "weather")
+    os.makedirs(weather_dir, exist_ok=True)
+    return os.path.join(weather_dir, f"{lat:.2f}_{lon:.2f}.json")
+
+
+def _is_fresh(path: str, max_age_hours: int = 6) -> bool:
+    """Return True if the cache file exists and is recent enough."""
+    if not os.path.exists(path):
+        return False
+    age = datetime.now().timestamp() - os.path.getmtime(path)
+    return age < max_age_hours * 3600
+
+
+def get_forecast(data_dir: str, api_key: str, lat: float, lon: float) -> list[dict]:
+    """Return 8-day daily forecast for lat/lon, caching results for 6 hours."""
+    cache_file = _cache_path(data_dir, lat, lon)
+
+    if _is_fresh(cache_file):
+        with open(cache_file) as f:
+            return json.load(f)  # type: ignore[no-any-return]
+
+    owm = pyowm.OWM(api_key)
+    mgr = owm.weather_manager()
+    result = mgr.one_call(lat=lat, lon=lon)
+
+    forecasts = []
+    for day in result.forecast_daily:
+        dt = datetime.fromtimestamp(day.ref_time)
+        temp = day.temperature("celsius")
+        forecasts.append(
+            {
+                "date": dt.date().isoformat(),
+                "status": day.status,
+                "detailed_status": day.detailed_status,
+                "temp_min": round(temp["min"]),
+                "temp_max": round(temp["max"]),
+                "precipitation_probability": day.precipitation_probability,
+                "icon": day.weather_icon_name,
+            }
+        )
+
+    with open(cache_file, "w") as f:
+        json.dump(forecasts, f)
+
+    return forecasts
+
+
+def trip_latlon(trip: object) -> tuple[float, float] | None:
+    """Return (lat, lon) for the primary destination of a trip, or None."""
+    from agenda.types import Trip
+
+    assert isinstance(trip, Trip)
+    for item in list(trip.accommodation) + list(trip.conferences):
+        if "latitude" in item and "longitude" in item:
+            return (float(item["latitude"]), float(item["longitude"]))
+    return None
+
+
+def get_trip_weather(data_dir: str, api_key: str, trip: object) -> dict[str, dict]:
+    """Return forecast for a trip keyed by date ISO string.
+
+    Returns an empty dict if no location is known or the API call fails.
+    """
+    latlon = trip_latlon(trip)
+    if not latlon:
+        return {}
+    lat, lon = latlon
+    try:
+        forecasts = get_forecast(data_dir, api_key, lat, lon)
+    except Exception:
+        return {}
+    return {f["date"]: f for f in forecasts}

templates/event_list.html

@@ -70,6 +70,19 @@
     Sunset: {{ sunset.strftime("%H:%M:%S") }}</li>
     </ul>
 
+  {% if home_weather %}
+  <div class="mb-2">
+    <strong>Bristol weather:</strong>
+    {% for day in home_weather %}
+      <span class="me-3 text-nowrap">
+        <small class="text-muted">{{ day.date_obj.strftime("%-d %b") }}</small>
+        <img src="https://openweathermap.org/img/wn/{{ day.icon }}.png" alt="{{ day.status }}" title="{{ day.detailed_status }}" width="25" height="25">
+        {{ day.temp_min }}–{{ day.temp_max }}°C
+      </span>
+    {% endfor %}
+  </div>
+  {% endif %}
+
   {% if errors %}
     {% for error in errors %}
       <div class="alert alert-danger" role="alert">

templates/macros.html

@@ -474,8 +474,16 @@ https://www.flightradar24.com/data/flights/{{ flight.airline_detail.iata | lower
 
     {{ conference_list(trip) }}
 
+    {% set trip_weather = trip_weather_map.get(trip.start.isoformat(), {}) if trip_weather_map is defined else {} %}
     {% for day, elements in trip.elements_grouped_by_day() %}
+      {% set weather = trip_weather.get(day.isoformat()) %}
       <h4>{{ display_date_no_year(day) }}
+        {% if weather %}
+          <small class="text-muted">
+            <img src="https://openweathermap.org/img/wn/{{ weather.icon }}.png" alt="{{ weather.status }}" title="{{ weather.detailed_status }}" width="25" height="25">
+            {{ weather.temp_min }}–{{ weather.temp_max }}°C {{ weather.detailed_status }}
+          </small>
+        {% endif %}
         {% if g.user.is_authenticated and day <= today %}
           <span class="lead">
             <a href="https://photos.4angle.com/search?query=%7B%22takenAfter%22%3A%22{{day}}T00%3A00%3A00.000Z%22%2C%22takenBefore%22%3A%22{{day}}T23%3A59%3A59.999Z%22%7D">photos</a>

templates/trip_page.html

@@ -377,6 +377,30 @@
       </div>
     {% endfor %}
 
+    {% if trip_weather %}
+    <div class="mt-3">
+    <h4>Weather forecast</h4>
+      {% set ns = namespace(has_rows=false) %}
+      <table class="table table-hover w-auto">
+      {% for day, elements in trip.elements_grouped_by_day() %}
+        {% set weather = trip_weather.get(day.isoformat()) %}
+        {% if weather %}
+        {% set ns.has_rows = true %}
+        <tr>
+          <td class="text-end text-nowrap">{{ display_date(day) }}</td>
+          <td><img src="https://openweathermap.org/img/wn/{{ weather.icon }}.png" alt="{{ weather.status }}" title="{{ weather.detailed_status }}" width="25" height="25"></td>
+          <td>{{ weather.temp_min }}–{{ weather.temp_max }}°C</td>
+          <td>{{ weather.detailed_status }}</td>
+        </tr>
+        {% endif %}
+      {% endfor %}
+      </table>
+      {% if not ns.has_rows %}
+        <p class="text-muted">Forecast not yet available (available up to 8 days ahead).</p>
+      {% endif %}
+    </div>
+    {% endif %}
+
     <div class="mt-3">
     <h4>Holidays</h4>
     {% if holidays %}

templates/weekends.html

@@ -12,8 +12,10 @@
         <th class="text-end">Date</th>
         <th>Saturday</th>
         <th>Saturday Location</th>
+        <th>Saturday Weather</th>
         <th>Sunday</th>
         <th>Sunday Location</th>
+        <th>Sunday Weather</th>
       </tr>
     </thead>
     <tbody>
@@ -51,6 +53,13 @@
           {{ city }}, {{ country.flag }} {{ country.name }}
         {% endif %}
       </td>
+      {% if extra_class %}<td class="{{ extra_class|trim }}">{% else %}<td>{% endif %}
+        {% set w = weekend[day + '_weather'] %}
+        {% if w %}
+          <img src="https://openweathermap.org/img/wn/{{ w.icon }}.png" alt="{{ w.status }}" title="{{ w.detailed_status }}" width="25" height="25">
+          {{ w.temp_min }}–{{ w.temp_max }}°C
+        {% endif %}
+      </td>
     {% endfor %}
     </tr>
   {% endfor %}

update.py

@@ -19,9 +19,11 @@ import agenda.geomob
 import agenda.gwr
 import agenda.mail
 import agenda.thespacedevs
+import agenda.trip
 import agenda.types
 import agenda.uk_holiday
 import agenda.uk_school_holiday
+import agenda.weather
 from agenda.event import Event
 from agenda.types import StrDict
 from web_view import app
@@ -406,6 +408,40 @@ def update_gandi(config: flask.config.Config) -> None:
         out.write(r.text)
 
 
+def update_weather(config: flask.config.Config) -> None:
+    """Refresh weather cache for all upcoming trips."""
+    from datetime import date, timedelta
+
+    today = date.today()
+    forecast_window = today + timedelta(days=8)
+
+    trips = agenda.trip.build_trip_list()
+    upcoming = [
+        t
+        for t in trips
+        if (t.end or t.start) >= today and t.start <= forecast_window
+    ]
+
+    seen: set[tuple[float, float]] = set()
+    count = 0
+    for trip in upcoming:
+        latlon = agenda.weather.trip_latlon(trip)
+        if not latlon or latlon in seen:
+            continue
+        seen.add(latlon)
+        lat, lon = latlon
+        try:
+            agenda.weather.get_forecast(
+                config["DATA_DIR"], config["OPENWEATHERMAP_API_KEY"], lat, lon
+            )
+            count += 1
+        except Exception as exc:
+            print(f"weather update failed for {lat},{lon}: {exc}")
+
+    if sys.stdin.isatty():
+        print(f"updated weather for {count} location(s)")
+
+
 def check_birthday_reminders(config: flask.config.Config) -> None:
     """Send at most one grouped birthday reminder email per day.
 
@@ -497,6 +533,7 @@ def main() -> None:
 
         agenda.fx.get_rates(app.config)
 
+        update_weather(app.config)
         update_thespacedevs(app.config)
 
         # Check for birthday reminders daily at 9 AM

web_view.py

@@ -31,6 +31,7 @@ import agenda.thespacedevs
 import agenda.trip
 import agenda.trip_schengen
 import agenda.utils
+import agenda.weather
 from agenda import ical, calendar, format_list_with_ampersand, travel, uk_tz
 from agenda.event import Event
 from agenda.types import StrDict, Trip
@@ -120,6 +121,7 @@ async def index() -> str:
         start_event_list=date.today() - timedelta(days=1),
         end_event_list=date.today() + timedelta(days=365 * 2),
         render_time=(time.time() - t0),
+        home_weather=get_home_weather(),
         **data,
     )
 
@@ -296,6 +298,15 @@ async def weekends() -> str:
     weekends = agenda.busy.weekends(
         start, busy_events, trip_list, app.config["PERSONAL_DATA"]
     )
+
+    home_weather = get_home_weather()
+    home_weather_by_date = {f["date"]: f for f in home_weather}
+    for weekend in weekends:
+        saturday = weekend["date"]
+        sunday = saturday + timedelta(days=1)
+        weekend["saturday_weather"] = home_weather_by_date.get(saturday.isoformat())
+        weekend["sunday_weather"] = home_weather_by_date.get(sunday.isoformat())
+
     return flask.render_template(
         "weekends.html",
         items=weekends,
@@ -583,6 +594,21 @@ def sum_distances_by_transport_type(trips: list[Trip]) -> list[tuple[str, float]
     return list(distances_by_transport_type.items())
 
 
+def get_home_weather() -> list[StrDict]:
+    """Get Bristol home weather forecast, with date objects added for templates."""
+    from datetime import date as date_type
+
+    forecasts = agenda.weather.get_forecast(
+        app.config["DATA_DIR"],
+        app.config.get("OPENWEATHERMAP_API_KEY", ""),
+        app.config["HOME_LATITUDE"],
+        app.config["HOME_LONGITUDE"],
+    )
+    for f in forecasts:
+        f["date_obj"] = date_type.fromisoformat(f["date"])
+    return forecasts
+
+
 def get_trip_list() -> list[Trip]:
     """Get trip list with route distances."""
     route_distances = agenda.travel.load_route_distances(app.config["DATA_DIR"])
@@ -674,11 +700,21 @@ def trip_future_list() -> str:
 
     shown = current + future
 
+    trip_weather_map = {
+        trip.start.isoformat(): agenda.weather.get_trip_weather(
+            app.config["DATA_DIR"],
+            app.config.get("OPENWEATHERMAP_API_KEY", ""),
+            trip,
+        )
+        for trip in shown
+    }
+
     return flask.render_template(
         "trip/list.html",
         heading="Future trips",
         trips=shown,
         trip_school_holiday_map=trip_school_holiday_map(shown),
+        trip_weather_map=trip_weather_map,
         coordinates=coordinates,
         routes=routes,
         today=today,
@@ -747,6 +783,12 @@ def trip_page(start: str) -> str:
                 app.config["PERSONAL_DATA"], route.pop("geojson_filename")
             )
 
+    trip_weather = agenda.weather.get_trip_weather(
+        app.config["DATA_DIR"],
+        app.config.get("OPENWEATHERMAP_API_KEY", ""),
+        trip,
+    )
+
     return flask.render_template(
         "trip_page.html",
         trip=trip,
@@ -760,6 +802,7 @@ def trip_page(start: str) -> str:
         holidays=agenda.holidays.get_trip_holidays(trip),
         school_holidays=agenda.holidays.get_trip_school_holidays(trip),
         human_readable_delta=agenda.utils.human_readable_delta,
+        trip_weather=trip_weather,
     )