Weather Wiz Kids
Provides great fundamental information on weather phenomena. Also includes great experiment ideas for teachers to conduct with students.
http://www.weatherwizkids.com

Web Weather for Kids
Weather-related games, activities, and stories can all be found on this site. This site is also great for creating ideas for weather forecasting.
http://eo.ucar.edu/webweather/

Weather Facts Page
This site provides interesting weather facts that students will surely be intrigued by.
http://weather-facts.com

The Weather Unit
This site contains various types of activities covering many topics including precipitation, evaporation, regional climates, and many more.
http://www.buildingrainbows.com/CA/ca.result.php

Weather for Teachers and Kids
This website includes many useful links for both teachers and their students to enjoy.
http://www.srh.noaa.gov/tsa/weather_kids.html

Jetstream
This website is by the National Weather Service and has experiments and activities for students to learn about weather.
http://www.srh.weather.gov/srh/jetstream/matrix.htm