Snapshot: First Day of Spring Snow, 2003-2008

This key will explain the color scheme on the maps in this series.

Water equivalent is a measure of snow that estimates the amount of water held in the snow. Think of it as the amount of water that would result if the snow melted instantly.

As the climate warms, spring is coming earlier to many parts of the world, including much of the United States. The growing season is longer, and snowpack that once held onto the mountains is melting earlier, resulting in greater fire risk, more drinking water supply worries and a greater need for summer irrigation of farmland.

These maps compare the amount of water locked in snow on the first day of Spring in each of the last six years.