So wouldn't it be great if you had a weather App with no Ads that would tell you if it was going to rain soon? Weather shots are key to great photography. It makes me wonder if a weather feature should be added to a Camera App.
Anyway, I found a solid App that does what you need. It's called Dark Sky
You can tell almost exactly when it will rain or snow up to an hour in advance. It is surprisingly accurate.
Now back to my idea for a Weather feature in a Camera App. Dark-Sky has an API for developers to integrate their data into their own Apps here: Dark Sky API And here are even More APIs. And the IBM Cloud has a Weather Company Data API.