I use Meteoblue as weather-App. It has a rain forecast and radar.

If it doesn’t have to be FOSS, I got the paid-once version of Today Weather, you can choose multiple data sources and it works with lots of countries, includes radar, windy.com, pollen count, Sun and moon rise and set, air quality, and is very pretty.

I quite like shadow weather and toss the dev $12/yr to maintain it. It has forecasts as well as radar

I use wX from f-droid. It uses data from the National Weather Service, so it might not be useful if you are located outside the US.

QuickWeather in fdroid has radar.

I use RadarNow! for my radar, it’s old school but so am I. Doesn’t show chance of rain but that’s a quick Google away anyway