Oh no! Another weather app. Actually, I'm thrilled at all the competition. WeatherPro has a great deal of information, far more than I see in most other weather apps. It is also very graphical in its approach, and a quick glance will show you a lot about the area your are interested in. WeatherPro for iPhone is on sale for US$1.99 (regular $3.99), and the iPad version is $2.99 (normally $4.99). [Note: Sale prices have ended]
Of course WeatherPro has a seven-day forecast with dynamic short-term forecasts, 2 million reporting locations from almost anywhere in the world, alerts and warning for extreme weather, sunrise and sunset time (a detail many apps leave out) and animated radar and satellite maps that are zoomable. It also features iCloud sync if you are running the app on multiple iOS devices, no limit to the number of locations you can display and the ability to use GPS to figure out your current location so you don't have to look it up.