See the other FieldScope projects at: FieldScope: Collaborative Mapping for Education
Precipitation and other climate data from U.S. weather stations is available as plots or to download in comma-separated variable format (CSV) for the date range 1895 to 2009 at US Historic Climate Network. An earlier version, Rev3, is also available to view the weather station data for temperature or precipitation for the 100 year period 1895-1994 at HCN Rev 3.
Learn more about My World GIS at www.myworldgis.org
Learn more about the Watershed Dynamics projects at www.globe.gov/watersheds
You can also try out Investigations II and IV of the Water Availability FieldScope tool. In Investigation II, you can study the different regions in the US and make selections of different amounts of precipitation. In Investigation IV several tables have already been filled so you can look at the seasonality of the data.