Want to know if it will rain today? Tomorrow? Did it rain yesterday? How much? 

If you're interested in precipitation statistics, visit the National Weather Service. These guys know weather. Seriously.

Check out their Advanced Hydrologic Prediction Service map. This map is updated every day and you can zoom in on your state. 

Advanced Hydrologic Prediction is, of course, just an extremely fancy weather geek way of saying "it might rain today," but the maps are cool and the information is extensive.

If you like the sound of advanced hydrologic prediction, be sure to check out the glossary section. Where else will you find the true definition of yellow snow (snow given a golden or yellow appearance by the presence in it of pine, cypress pollen, or anthropogenic material or animal-produced material) or a handy hail size chart that gives you the actual dimensions of pea, walnut, teacup and softball-sized ice balls?