Description of Normals Maps

This directory contains maps of climate normals for the state of Montna for the 1991 - 2020 reference period. All normals are derived from gridMET climate data. The data were projected to Montana State Plane and some units were transformed from metric to imperial for display. The units and variable names associated with each of the sub-directories are listed in the table below:

Abbreviation Long Name Units
erc Energy Release Component NFDRS fire danger index
pr Precipitation in
rmax Maximum Relative Humidity %
rmin Minimum Relative Humidity %
sph Specific Humidity kg/kg
srad Solar Radiation W/m^2
tmmn Minimum Temperature deg F
tmmx Maximum Temperature deg F
vpd Vapor Pressure Deficit kPa
vs Wind Speed m/s

Within each subdirectory, files adhere to a naming convention of {time}_{statistic}.tif, where time is the time period of the normal (e.g., annual, jan, feb, etc.) and statistic is the climate normal summary statistic (e.g., mean, median, etc).

For more details about how the climate normals were created, please visit the information tab on the Montana Climate Atlas. If you have any other questions about the data, please reach out to Colin Brust at the Montana Climate Office (