CNN Weather
http://www.cnn.com/weather

USA Today Weather
http://www.usatoday.com/weather/forecast/us-states/us-states-index.htm

Weather.com - Worldwide weather conditions.
http://www.weather.com

Wunderground.com - Find the weather for any city, state, ZIP code, or country; in many languages.
http://www.wunderground.com