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.
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.