Specifically for agriculture, this weather site includes precipitation, temperature, winds, surface maps, and degree days. Provided by John Deere.
Cotton Belt Soil Moisture Conditions
Updated weekly by the National Oceanic and Atmospheric Administration.
National Weather Service
The National Oceanic Atmospheric Administration's National Weather Service.
NOAA's Drought Information Center
A roundup of information on drought and climate conditions.
The Weather Channel
USDA NASS Weekly Crop Weather
Includes crop progress reports, weekly weather, and crop bulletins.