PRISM 30-year normals are baseline datasets describing average monthly and annual conditions over the most recent three full decades. They are our most popular datasets. The current normals cover the period 1991-2020, for the conterminous US (48 states).

Long-term average datasets are modeled using a digital elevation model (DEM) as the predictor grid. Given their importance, the normals are subjected to extensive peer review. Data available from this page is type "Norm91m" -- see our PRISM Datasets document for more information.

PRISM normals for Alaska, Hawaii/US Pacific Islands, Puerto Rico, US Virgin Islands, Jamaica, and western Canada are available in the Projects section.