Caroline Haskins, writing at The Outline, gets into why some weather apps seem to get things wrong so often:
Thousands of these events occur around the world each day, and there isn’t the human infrastructure to provide individual attention to each event.
This means that a large portion of weather forecasts on apps end up being dictated by computer models, which can’t explain their reasons for making a forecast. Users have no way of knowing whether their local forecast has been reviewed by a human.
And of course, not all forecasts are equal. According to 2016 research from Forecast Watch, the best forecast services for one to three day forecasts are Weather Underground, The Weather Channel (which owns Weather Underground), and Accuweather, which are accurate about 75 percent of the time. In comparison, Dark Sky and World Weather Online, the eighth and ninth most accurate forecasting services, are accurate 64 to 67 percent of the time.
For what it’s worth, I use Carrot Weather plugged into Weather Underground.