For a while now I've been using #Forecastie to display open weather data from;
It was, at the time, the best weather app I could find on F-Droid. But while I was Fossify-ing my Simple apps, I decided to see what's available now. I'm quite impressed with Breezy Weather (forked from Geometric Weather);
https://f-droid.org/packages/org.breezyweather/
It seems to be able to use a range of open data sources, but the default appears to be;