You can unlock professional Apple Weather, Foreca, Open-Meteo, and Dark Sky forecast sources, weather alerts, nowcast, and all styles and options via a reasonably priced subscription, which covers the cost of data and allows me to further improve Weathergraph.
Weathergraph is offline capable - the app caches the last acquired forecast for up to 24 hours, allowing you to hike or run outside of the network (or go running or biking with a wifi-only Apple Watch) and still see the most recently fetched data.
Weathergraph is a beautiful visual hourly weather widget and forecast for Watch, iPhone, iPad, and Mac, with the Apple Watch app and complications.
If rain or snow is expected during the next 3 hours, you will get a notice on a widget (iPhone, iPad & Mac), a large complication (Watch), and a detailed 3-hour precipitation chart in the app.
Hourly forecast is updated every hour, nowcast and rain alerts update every 15 minutes.