General Weather
Weather Science Hotlist
http://sln.fi.edu/tfi/hotlists/weather.html
This site from the Franklin Institute is a comprehensive listing of many weather sites.

Earthquakes
Exploratorium Learning Studio
http://www.exploratorium.edu/ls/pathfinders/earthquakes
This is a child-friendly site from the Exploratorium that explains the earthquake in simple, easy-to-understand language.  It has great graphics that can be used for reports.

Hurricanes
The Miami Science Museum
http://www.miamisci.org/hurricane/insideahurricane.html
Designed by the Miami Science Museum, this site provides wonderful graphics so that students can go inside a hurricane and learn about its phases.

Volcanoes
The U.S. Geological Service
http://vulcan.wr.usgs.gov/LivingWith/framework.html
Provided by the U.S. Geological Service at the Cascades Volcano Observatory, this is an all-inclusive site that includes a explanation of how volcanoes work, types of volcanoes and how they are monitored.  Graphic representations are available for reports.

Tornadoes
USA Today
http://www.usatoday.com/weather/tornado/wtwist0.htm
USA Today provides in-depth material on tornadoes, including different types of tornadoes and the causes.  This is a very up-to-date site with material being added daily.