In the US, the National Oceanic and Atmospheric Administration's National Weather Service provides one of the most accurate forecasts available. Even though that's the case, they are forbidden by law from creating a smartphone app.

You can thank weather forecasting cable channels and websites for that. Even though they use NOAA's data, they didn't want competition from the best weather forecasting service. So, they bought themselves a law and that means worse service for all of us.