Weather Channel should show you, but I know Beautiful Widget and the HTC Weather/Clock Widget combo shows when it's raining if you just happen to not be able to look outside currently. I would suggest if you have the HTC Droid Eris, or the HTC Hero (it should be on there as well seeing as how the Hero/Eris are the same) to use the HTC W/C combo. But if you want the same thing as the HTC W/C combo get Beautiful Widgets but with BW you can have custom skins on the clock.