Climate Maps for Illinois

Jim Angel, state climatologist

These maps describe the climate of Illinois using the 1971-2000 average or "normals". Available maps include temperature, precipitation, snowfall, heating-, cooling-, and growing-degree days, as well as frequency of days at various thresholds of temperature, precipitation and snowfall. These maps may be reproduced and redistributed, crediting the Illinois State Water Survey (see data disclaimer).

Precipitation (inches)
Jan	Feb	Mar	Apr	May	Jun
Jul	Aug	Sep	Oct	Nov	Dec	Annual
Mean Daily High Temperature (degrees F)
Jan	Feb	Mar	Apr	May	Jun
Jul	Aug	Sep	Oct	Nov	Dec	Annual
Mean Daily Low Temperature (degrees F)
Jan	Feb	Mar	Apr	May	Jun
Jul	Aug	Sep	Oct	Nov	Dec	Annual
Mean Daily Temperature (degrees F)
Jan	Feb	Mar	Apr	May	Jun
Jul	Aug	Sep	Oct	Nov	Dec	Annual
Snowfall (inches)
Jan	Feb	Mar	Apr	May	Jun
Jul	Aug	Sep	Oct	Nov	Dec	Annual
Heating Degree Days
Jan	Feb	Mar	Apr	May	Jun
Jul	Aug	Sep	Oct	Nov	Dec	Annual
Cooling Degree Days
Jan	Feb	Mar	Apr	May	Jun
Jul	Aug	Sep	Oct	Nov	Dec	Annual
Growing Degree Days
Jan	Feb	Mar	Apr	May	Jun
Jul	Aug	Sep	Oct	Nov	Dec	Annual

Days At Selected Temperature Thresholds
Days at or above 90F	Days at or above 100F	Days at or below 32F	Days at or below 0F
Days At Selected Precipitation Thresholds
Days precipitation at or above 0.01 inches	Days precipitation at or above 0.25 inches	Days precipitation at or above 1.00 inches
Days At Selected Snowfall Thresholds
Days snowfall at or above 1 inches	Days snowfall at or above 6 inches

See frost and growing season page for information on those two topics.

The data used in these products come from the National Weather Service (NWS) Cooperative Observer Program (COOP). This network of more than 11,000 volunteer observers nationwide, using approved instruments and observing techniques, provides high-quality climate data to the nation. The data are archived at the National Climatic Data Center (NCDC).