Illinois design temperatures
Outdoor heating and cooling design conditions for 10 Illinois weather stations. Choose the station nearest to you in distance and elevation, and check whether your building department specifies its own values.
| Station | Elevation | 99.6 % heating | 99 % heating | 1 % cooling / MCWB | 0.4 % cooling / MCWB | Use it |
|---|---|---|---|---|---|---|
| Champaign/UrbanaWMO 725315 · 1973–1996 | 755 ft | −3 °F | 3 °F | 90 / 75 °F | 93 / 77 °F | Load calculator |
| Chicago/MidwayWMO 725340 · 1973–1996 | 623 ft | −4 °F | 2 °F | 89 / 73 °F | 92 / 75 °F | Load calculator |
| Chicago/O'HareWMO 725300 · 1967–1996 | 673 ft | −6 °F | 0 °F | 89 / 73 °F | 92 / 75 °F | Load calculator |
| DecaturWMO 725316 · 1973–1996 | 682 ft | −2 °F | 3 °F | 91 / 76 °F | 93 / 77 °F | Load calculator |
| GlenviewWMO 725306 · 1973–1995 | 653 ft | −4 °F | 1 °F | 89 / 73 °F | 92 / 75 °F | Load calculator |
| Moline/Quad CityWMO 725440 · 1973–1996 | 594 ft | −9 °F | −3 °F | 90 / 75 °F | 93 / 76 °F | Load calculator |
| PeoriaWMO 725320 · 1973–1996 | 663 ft | −6 °F | 0 °F | 90 / 75 °F | 92 / 76 °F | Load calculator |
| Scott AFB/BellevilleWMO 724338 · 1967–1996 | 453 ft | 3 °F | 9 °F | 92 / 76 °F | 95 / 78 °F | Load calculator |
| Springfield/CapitalWMO 724390 · 1973–1996 | 614 ft | −4 °F | 2 °F | 91 / 76 °F | 94 / 77 °F | Load calculator |
| West Chicago/Du PageWMO 725305 · 1973–1996 | 758 ft | −7 °F | −2 °F | 88 / 73 °F | 91 / 75 °F | Load calculator |
Using these values
- Heat-loss calculations for homes commonly use the 99 % heating value, and cooling loads the 1 % dry bulb with its mean coincident wet bulb (MCWB). The 99.6 % and 0.4 % values are more conservative.
- “Load calculator” opens the heating and cooling load calculator with that station’s 99 % and 1 % temperatures and its design moisture difference (outdoor air at the 1 % condition versus 75 °F, 50 % RH indoors, at the station’s elevation).
- Source: U.S. Air Force Combat Climatology Center and NOAA National Climatic Data Center, Engineering Weather Data (1999; public domain). Each station’s period of record is shown under its name; they end by 1996, and the climate has warmed since, so check local requirements before relying on a value for a permit.