Climate averages 1991–2020
Evanston weather
in September.
A warm, moderately wet month: the 4th warmest and the 6th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Evanston: daytime highs average 22.1°C and nights cool to about 16.4°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 74 mm of rain on roughly 9 days, which makes September a moderately wet month (the 6th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 32 min on an average September day.
The nearest other city in this atlas is Chicago (22 km away). In September its highs average 22.7°C, 0.6°C warmer than Evanston, with 75 mm of rain.
Among the 498 cities listed in the United States, Evanston ranks joint 451st of 498 for the warmest September highs and joint 241st of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Evanston is 4.8°C cooler than that mean.
From September to October, average highs fall by 6.8°C to 15.3°C, and monthly rainfall rises from 74 mm to 83 mm.
The annual picture
September in context
Monthly precipitation
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Evanston climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -1.0°C-7.0°C | -7.0°C | 58 | 9.1 | 9.59 h |
| February | 0.3°C-6.2°C | -6.2°C | 52 | 7.3 | 10.511 h |
| March | 4.8°C-1.5°C | -1.5°C | 66 | 10.0 | 11.912 h |
| April | 10.9°C4.4°C | 4.4°C | 108 | 11.9 | 13.313 h |
| May | 17.7°C11.0°C | 11.0°C | 104 | 12.0 | 14.515 h |
| June | 23.8°C17.5°C | 17.5°C | 92 | 11.8 | 15.215 h |
| July | 26.7°C20.7°C | 20.7°C | 86 | 11.3 | 14.915 h |
| August | 25.8°C20.3°C | 20.3°C | 92 | 10.6 | 13.914 h |
| September, selected | 22.1°C16.4°C | 16.4°C | 74 | 8.9 | 12.513 h |
| October | 15.3°C9.8°C | 9.8°C | 83 | 9.4 | 11.111 h |
| November | 7.9°C2.8°C | 2.8°C | 67 | 8.8 | 9.910 h |
| December | 2.0°C-3.0°C | -3.0°C | 59 | 8.8 | 9.29 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Chicago in SeptemberUnited States · 22 kmHigh 22.7°C · Low 15.8°C · 75 mm rain
- Cicero in SeptemberUnited States · 22 kmHigh 23.1°C · Low 15.2°C · 75 mm rain
- Arlington Heights in SeptemberUnited States · 25 kmHigh 22.7°C · Low 15.1°C · 75 mm rain
- Schaumburg in SeptemberUnited States · 32 kmHigh 22.9°C · Low 14.2°C · 75 mm rain
- Waukegan in SeptemberUnited States · 38 kmHigh 21.2°C · Low 17.1°C · 83 mm rain
- Naperville in SeptemberUnited States · 47 kmHigh 23.1°C · Low 14.3°C · 77 mm rain
- Elgin in SeptemberUnited States · 49 kmHigh 23.1°C · Low 14.3°C · 78 mm rain
- Bolingbrook in SeptemberUnited States · 49 kmHigh 23.2°C · Low 14.3°C · 74 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Evanston) is explained once on the Evanston year overview and on the Sources, method and limits page.