Hello! I'm looking for a foss weather app for android, so I went ahead to f-droid and tried a bunch of them, but didn't find any that fully satisfies me: I want to be able to see the hourly forecast of any day of the week, not just the "global" forecast, and I want the weather service used not to require a credit card (openweathermap.org for example requires the credit card to get an API key). Geometric Weather is the one that I'm currently using, with open-meteo as provider, but sadly it displays hourly forecasts only for the current day, but not for other days.
The Breezy Weather (fdroid link) is a fork and continuation of GeometricWeather. As I can see, there are hourly forecasts for the next days, just scroll horizontally (AccuWeather and Open-Meteo providers, tho, I haven't checked others).
I just wish it had a precipitation radar. I'm pretty sure the data is available because I've seen another FOSS app that had it, but I can't remember which now.
Not FOSS, but did you know you can get your weather forecasts straight from the source? Weather.gov gives not only a standard 7 day forecast but also provides all sorts of weather data and lots of the charts on the site is designed to be customized then bookmarked even if your browser has cookies disabled!
Not FOSS, but free and ad-free, from a small Japanese developer: Weawow. The only thing that requires you to make a small donation is to unlock a couple of weather providers, but you have a big selection without it.