Climate averages 1991–2020
Springfield (Illinois), United States weather
in September.
A warm, moderately wet month: the 4th warmest and the joint 5th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Springfield (Illinois), United States: daytime highs average 25.2°C and nights cool to about 15.5°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 80 mm of rain on roughly 7 days, which makes September a moderately wet month (the joint 5th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 30 min on an average September day.
The nearest other city in this atlas is Decatur (59 km away). In September its highs average 25.0°C, about as warm as Springfield (Illinois), United States, with 82 mm of rain.
Among the 498 cities listed in the United States, Springfield (Illinois), United States ranks joint 306th of 498 for the warmest September highs and joint 277th of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Springfield (Illinois), United States is 1.7°C cooler than that mean.
From September to October, average highs fall by 6.8°C to 18.4°C, and monthly rainfall rises from 80 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
Springfield (Illinois), United States climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 1.9°C-6.2°C | -6.2°C | 61 | 8.0 | 9.710 h |
| February | 4.7°C-4.6°C | -4.6°C | 57 | 7.6 | 10.711 h |
| March | 10.9°C0.8°C | 0.8°C | 80 | 10.0 | 11.912 h |
| April | 17.4°C6.9°C | 6.9°C | 116 | 11.9 | 13.213 h |
| May | 22.7°C13.0°C | 13.0°C | 117 | 13.3 | 14.314 h |
| June | 27.4°C18.0°C | 18.0°C | 110 | 11.4 | 14.915 h |
| July | 29.1°C20.2°C | 20.2°C | 91 | 10.1 | 14.715 h |
| August | 28.6°C19.5°C | 19.5°C | 78 | 9.3 | 13.714 h |
| September, selected | 25.2°C15.5°C | 15.5°C | 80 | 7.4 | 12.512 h |
| October | 18.4°C9.2°C | 9.2°C | 83 | 8.5 | 11.211 h |
| November | 10.7°C2.4°C | 2.4°C | 84 | 8.3 | 10.010 h |
| December | 4.4°C-3.1°C | -3.1°C | 59 | 8.0 | 9.49 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
- Decatur in SeptemberUnited States · 59 kmHigh 25.0°C · Low 15.4°C · 82 mm rain
- Bloomington (Illinois), United States in SeptemberUnited States · 94 kmHigh 24.3°C · Low 14.8°C · 77 mm rain
- Peoria (Illinois), United States in SeptemberUnited States · 99 kmHigh 24.4°C · Low 15.4°C · 76 mm rain
- Champaign in SeptemberUnited States · 124 kmHigh 24.7°C · Low 14.9°C · 77 mm rain
- St. Louis in SeptemberUnited States · 139 kmHigh 26.4°C · Low 16.6°C · 83 mm rain
- O'Fallon in SeptemberUnited States · 143 kmHigh 26.0°C · Low 16.7°C · 81 mm rain
- Davenport in SeptemberUnited States · 207 kmHigh 23.8°C · Low 14.8°C · 88 mm rain
- Joliet in SeptemberUnited States · 232 kmHigh 23.8°C · Low 14.5°C · 75 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 Springfield) is explained once on the Springfield (Illinois), United States year overview and on the Sources, method and limits page.