hetweer.nu: measurements and forecast in one graph

The idea

Most weather apps show a single forecast, as if it were certain. hetweer.nu shows the uncertainty instead, next to what was actually measured.

What I build

• A forecast plume per place. The forecast line is the median of 50 ECMWF ensemble members. A band shows where 80% of the members fall, so you can see how certain the forecast is.
• Measurements next to the forecast. The latest measurements from the nearest KNMI station sit in the same graph, and the earlier forecast stays visible. You can see right away how well it holds up.
• A page for every place. Use your location, save favourites or browse by province, with place names from PDOK.

The backend runs on FastAPI, the front-end is built with React, and everything is hosted on Google Cloud Run. The data comes from KNMI Open Data and ECMWF Open Data.