1Weather is about as complete of a weather app as you can find. It comes with all kinds of stuff including current conditions, forecasts, radar, predictions, fun facts about meteorology, graphs, and even a sun and moon tracker.
The design is gorgeous as well and the app includes fairly decent and somewhat configurable widgets. It’s free to use and the $1.99 charge is simply to remove advertising. As long as you don’t mind the occasional banner add, you get all of the features in the free version.