Map: monthly average precipitation

This map shows total rain and snowfall in the contiguous United States, every month from 1981 to the present. The map’s color scale runs from white (no precipitation), to blue (significant precipitation) to red (intense precipitation).

The resolution of the data is about 800 meters (around a half-mile) per pixel. For the purposes of download time, the resolution of the image on the map has been reduced to four kilometers per pixel (about 2.5 miles). 


Data on precipitation in the Contiguous U.S. is taken from the PRISM Climate Group at Oregon State University, which uses weather station data and a sophisticated interpolation model to produce monthly and daily precipitation for the contiguous U.S. at about 800-meter resolution. 

For the most recent six months of data, we use their provisional data, and their more stable data for earlier months. We use these data to calculate monthly totals each state, and monthly averages since 1981.

See this post to learn more about this dashboard and other interactive visualizations.