I’m not sure if this is too local for a weather service, and might be too much to have many local API for small places like Sweden.
Anyway this is the official Swedish weather service, SMHI, it should be free for commercial use with attribution.
It has multiple APIs, warnings, forecast, analysis, there are some APIs that cost money but I don’t think those matter here. There are some smaller issues with the API (imo), misspellings and such but they are quick to reply in my experience, I contacted them about oktas being spelled wrong(they spelled it octas), and they replied in less than a day saying they would fix it after summer vacations.