Gradient Weather

Man! Dark Sky was the best weather app ever, wasn't it?

This isn't quite as good (close, though!), but it's good looking (very customizable), has nice widgets, let's you report current conditions on a map (which is fun), and there are a bevy of notification options.

(I opted to pay for the lifetime upgrade just to have all the features/notifications, but it's free if you don't care about having all the things.)