Chicago weather in September: Chicago, Illinois: normal highs, lows, rain and records for September
Chicago in September has a normal high of 76°F and a normal low of 57°F, a daily mean of 66°F, falling from 80°F on the 1st to 70°F by the 30th. Measurable precipitation falls on 9 days in a normal September, 3.19 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 24°C and low of 14°C, 81 mm of precipitation in September.
- NOAA stationChicago O'Hare International Airport
- Station IDUSW00094846
- Location41.99°N 87.93°W
- Elevation658 ft (201 m)
- From the center17 miles
- Population2,721,308
- Jan 32° 19°
- Feb 36° 22°
- Mar 47° 31°
- Apr 59° 40°
- May 71° 51°
- Jun 80° 61°
- Jul 85° 66°
- Aug 83° 65°
- Sep 76° 57°
- Oct 63° 45°
- Nov 48° 34°
- Dec 37° 24°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Chicago in September?
The normal high is 76°F and the normal low 57°F, for a daily mean of 66.3°F. September is 7.5°F cooler than August and 12.3°F warmer than October. September is the 4th warmest month of the year in Chicago and the 7th wettest. Across the month the normal high falls 10°F, from 80°F on September 1 to 70°F on September 30. From one year to the next September's mean temperature typically moves about 2.5°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 64°F and 69°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 31%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 80°F | 62°F | 29% | 19% |
| September 8 | 78°F | 60°F | 29% | 19% |
| September 15 | 76°F | 58°F | 29% | 19% |
| September 22 | 73°F | 55°F | 30% | 20% |
| September 30 | 70°F | 51°F | 31% | 20% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 80°F | 62°F | 29% | 19% | 13 h 10 min |
| September 2 | 80°F | 62°F | 28% | 19% | 13 h 10 min |
| September 3 | 80°F | 62°F | 28% | 19% | 13 h 10 min |
| September 4 | 80°F | 62°F | 28% | 19% | 13 h |
| September 5 | 79°F | 61°F | 28% | 19% | 13 h |
| September 6 | 79°F | 61°F | 29% | 19% | 13 h |
| September 7 | 79°F | 61°F | 29% | 19% | 13 h |
| September 8 | 78°F | 60°F | 29% | 19% | 12 h 50 min |
| September 9 | 78°F | 60°F | 29% | 19% | 12 h 50 min |
| September 10 | 78°F | 59°F | 29% | 19% | 12 h 50 min |
| September 11 | 77°F | 59°F | 29% | 19% | 12 h 40 min |
| September 12 | 77°F | 59°F | 29% | 19% | 12 h 40 min |
| September 13 | 77°F | 58°F | 29% | 19% | 12 h 40 min |
| September 14 | 76°F | 58°F | 29% | 19% | 12 h 40 min |
| September 15 | 76°F | 58°F | 29% | 19% | 12 h 30 min |
| September 16 | 76°F | 57°F | 29% | 19% | 12 h 30 min |
| September 17 | 75°F | 57°F | 29% | 19% | 12 h 30 min |
| September 18 | 75°F | 56°F | 29% | 20% | 12 h 20 min |
| September 19 | 74°F | 56°F | 30% | 20% | 12 h 20 min |
| September 20 | 74°F | 55°F | 30% | 20% | 12 h 20 min |
| September 21 | 74°F | 55°F | 30% | 20% | 12 h 20 min |
| September 22 | 73°F | 55°F | 30% | 20% | 12 h 10 min |
| September 23 | 73°F | 54°F | 30% | 20% | 12 h 10 min |
| September 24 | 72°F | 54°F | 30% | 20% | 12 h 10 min |
| September 25 | 72°F | 53°F | 30% | 20% | 12 h 10 min |
| September 26 | 72°F | 53°F | 30% | 20% | 12 h |
| September 27 | 71°F | 53°F | 31% | 20% | 12 h |
| September 28 | 71°F | 52°F | 31% | 20% | 12 h |
| September 29 | 70°F | 52°F | 31% | 20% | 11 h 50 min |
| September 30 | 70°F | 51°F | 31% | 20% | 11 h 50 min |
- Normal high
- 76°FSeptember average
- Normal low
- 57°FSeptember average
- Precipitation
- 3.19 inmonth total
- Days with precipitation
- 90.01 inch or more
- Days at 90°F or more
- 2
- Daylight
- 13 h 10 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 22
- Days at 80°F or more
- 10
- Sunshine
- 79%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00094846; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Chicago in September?
On a given September day the chance of 0.01 inch or more is 29% on average, highest around September 30 (31%). In all, 3.19 in falls on 9 days of a normal September, 1 of them with an inch or more.
In a normal September in Chicago, 2 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00094846.
How humid and windy is Chicago in September?
At 3 p.m. the normal temperature is 67°F with 51% relative humidity and a dew point of 48°F; at 6 a.m. it is 53°F with 83% humidity. The wind averages 9.0 mph, most often from the west in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 53°F | 48°F | 83% | 7.2 mph | 35% |
| 9 a.m. | 60°F | 49°F | 67% | 10.1 mph | 38% |
| noon | 66°F | 48°F | 54% | 11.4 mph | 27% |
| 3 p.m. | 67°F | 48°F | 51% | 11.6 mph | 30% |
| 6 p.m. | 62°F | 48°F | 61% | 9.1 mph | 36% |
| 9 p.m. | 58°F | 49°F | 71% | 8.4 mph | 52% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00094846. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in Chicago?
The warmest September temperature on Chicago's official record (since 1872) is 101°F, on September 2, 1953; the coldest is 29°F, on September 28, 1942. The wettest September brought 14.17 in (1961).
The September mean against the 1991-2020 normal of 66.3°F: 2021 70.3°F (+4.0), 2022 67.4°F (+1.1), 2023 69.5°F (+3.2), 2024 70.6°F (+4.3), 2025 69.3°F (+3.0), 2026 70.1°F (+3.8). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 70.3°F | +4.0°F | 1.23 in |
| 2022 | 67.4°F | +1.1°F | 2.20 in |
| 2023 | 69.5°F | +3.2°F | 3.36 in |
| 2024 | 70.6°F | +4.3°F | 1.32 in |
| 2025 | 69.3°F | +3.0°F | 0.49 in |
| 2026 | 70.1°F | +3.8°F | 3.70 in |
Source: records: ACIS, NWS threaded record ORDthr; recent months: ACIS, station USW00094846. Records and recent months use complete months only.
How does September in Chicago compare across Illinois?
Across the 144 places PlainClimate covers in Illinois, September normal highs run from 72°F in Barrington to 84°F in Anna; Chicago's is 76°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.