The climate is a hot issue and weather forecasting technology is suddenly cool. The urgent need for innovative weather and environmental conditions forecasting solutions is obvious whether you believe in climate change or not.
Thanks for putting together a good weather API list. You said to leave a comment for missed entries, and you missed one of my favorites - Visual Crossing weather (https://www.visualcrossing.com/weather-api). It provides weather history data, a 15-day forecast, and starts at $5/mo after the free trial. The query page lets you view results and download weather data directly in CSV or JSON. It will also automatically generate your API query URL for use in application code.
It seems to me that this is one of the lowest cost weather data options out there with a lot of functionality, but in any case, it at least merits consideration in the list.