Heavy to excessive rainfall over the southern Appalachians may bring areas of flooding Tuesday. Hot to extremely hot temperatures are in place through Tuesday across much of the western U.S. and northern New England. Tropical Storm Erin is forecast to become a Major Hurricane by this weekend as it moves across the central Atlantic Ocean. Monitor future forecasts for any East Coast impacts. Read More >
Coverage is affected by many factors.
Read the Coverage Map Notes below to understand these factors on the state and individual maps.
The coverage statistics and maps are calculated using a computer model and station data, assuming ideal conditions. Actual coverage may be 5 to 10 percent below the computer-predicted coverage due to the following factors: