US-only, I've had good luck with the NWS JSON API[1]. Someone posted a while ago on here[2] about taking in various NWS models and creating "Pirate Weather"[3], a drop-in replacement for Dark Sky.

1. https://www.weather.gov/documentation/services-web-api

2. https://news.ycombinator.com/item?id=34329988

3. https://pirateweather.net/