Hot, Humid Weather in Illinois
The information here tells how often heat combines with humidity in Illinois cities to create uncomfortably muggy weather.
The apparent temperature, also known as the Heat Index, measures how hot the weather really feels, considering both temperature and humidity. For instance, a temperature of 90 degrees Fahrenheit (32.2 ° Celsius) along with 60 % humidity pushes the apparent temperature to 100 °F (37.8 °C).
These tables list the number of days when the actual temperature and the apparent temperature rose to least 95, 105 or 115 °F (35, 40.6 or 46.1 °C) for an hour or more. The totals are for the 30 years from 1978 to 2007.
The final table breaks the totals into yearly averages for the days when apparent temperatures reach 95 and 105 °F.
| City | Actual | Apparent |
|---|---|---|
| Chicago | 93 | 375 |
| Moline | 154 | 592 |
| Peoria | 117 | 592 |
| Quincy | 174 | 658 |
| Rockford | 76 | 351 |
| Springfield | 130 | 707 |
| City | Actual | Apparent |
|---|---|---|
| Chicago | 0 | 60 |
| Moline | 0 | 116 |
| Peoria | 0 | 123 |
| Quincy | 2 | 123 |
| Rockford | 0 | 54 |
| Springfield | 0 | 145 |
| City | Actual | Apparent |
|---|---|---|
| Chicago | 0 | 3 |
| Moline | 0 | 5 |
| Peoria | 0 | 6 |
| Quincy | 0 | 9 |
| Rockford | 0 | 3 |
| Springfield | 0 | 12 |
| City | 95+ °F | 105+ °F |
|---|---|---|
| Chicago | 13 | 2 |
| Moline | 20 | 4 |
| Peoria | 20 | 4 |
| Quincy | 22 | 4 |
| Rockford | 12 | 2 |
| Springfield | 24 | 5 |
References
Peter Browning and Brian Walawender. 2009. A Climatology of Apparent Temperature. 21st Conference on Climate Variability and Change.