Mean annual temperature in the Chicago area is projected to increase by 2.3 ° to 8.2 ° F by the end of the 21st century, with temperature increases across all seasons.

Mean annual daily temperature across the region is projected to increase by 8.2 °F (4.5 °C) under the GFDL A1FI (high emissions) scenario and 2.3 °F (1.2 °C) under PCM B1 (low emissions) for the final 30 years of the 21st Century compared to the 1971 to 2000 baseline. The most dramatic increase in temperature is projected to be in winter for the PCM B1 scenario and summer for the GFDL A1FI scenario. No spatial variation in temperature changes across the Chicago Wilderness region is discernable. Increases are projected to be slightly greater in minimum temperatures than maximum temperatures, with the exception of summer under the GFDL A1FI scenario.