Accuweather, find it to be highly accurate with all the benefits of the paid apps, the radar is spot on, with both past and predictive modes. Rain notice, how long to rain, how long it will last and strength projections during that period are a graphic,
and again, free...

Also use MyRadar for an exclusive active radar mode application without all the forecast information. Usually run it while on the motorcycle and the afternoon showers start popping up in order to determine the dryest possible route.

Both are free.

I've had it for several years and I find it to be pretty accurate. I haven't purchased many apps but it is the only one I can think of that I still use daily.

I’ve used it for about three years. The owner of Della Terra resort in Estes Park recommended it to me. He does many outdoor weddings and likes the accuracy of it. I use it along with Weather underground.

 
I've used the app on my iPhone for a couple of years now. I consider it a very good app, especially now that they've got the wind direction arrows correct. They used to have the arrow pointing into the wind, which to my mind is ass backwards. Now they use the arrow to show the wind's direction, like almost every other weather site.
 
Their web site is also nice. It uses the same layout and graphics as the mobile app. To make it more useful, I input my GPS coordinates in the location box, and saved that URL as my bookmark.