You can instantly see the weather for the entire day (24h) in two circles of 12h each. A yellow arc shows when the sun is up. A blue arc when present shows rainfall, with a thicker line meaning lots of rain.
Weather data is supplied by Open-Meteo (https://open-meteo.com/) which I found out about via a Show HN.
The source code is on Github: https://github.com/boxed/frej