If you are in the United States, nothing beats getting the forecast straight from the horses mouth (NWS that is). Some companies are notorious for producing 30+ day forecasts, which can't have any meaningful levels of skill.
NOAA/NWS should just create their own mobile application. I use Wx[1], which parses NWS data directly and can be found on f-droid[2] and g---le play.
Granted, Wx doesn't follow Material Design for Android in the slightest, but I like it that way because it's very information-dense, snappy, and light (unlike r--ct "native" and other JS toolkits out there).
[0]: https://news.ycombinator.com/item?id=19775291