Dark Sky will still be available for $99/year and will allow 500,000 queries per month at that price. See https://developer.apple.com/weatherkit/get-started/
https://pirateweather.net is a drop-in replacement for the Dark Sky API and uses NOAA data provided by AWS’s open data program (https://registry.opendata.aws/collab/noaa/). It includes NOAA High Resolution Rapid Refresh (HRRR) data, which provides 15-minute forecasts out to 48 hours for the continental US, southern Canada, and northern Mexico in 3 km increments. (GFS, with 18 km resolution, is used for the rest of the world.) Precipitation probabilities are computed using the Global Ensemble Forecast System (GEFS). By running different variations parameters and inputs, 30 different versions of this model are run at the same time, providing 3-hour forecasts out to 240 hours. Since this is a 30-member ensemble, if 1 member predicts precipitation, the precipitation probability will be 1/30. (You can use https://weather.pirateweather.net to see the data on the web.)