Chicago, IL weather in September
September in Chicago: mild, with some rain. Highs 77°F, lows 59°F, about 8 wet days. A good month for most outdoor plans.
- Normal high
- 77°F
- Normal low
- 59°F
- Wet days
- 8
- 3.3 in total
- Muggy days
- 3
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 81°F | 71°F |
| Normal low | 64°F | 53°F |
| Chance of a wet day | 28% | 30% |
| Sunrise / sunset | 6:16 am / 7:24 pm | 6:46 am / 6:34 pm |
| Daylight | 13.1 h | 11.8 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Central Time).
A typical September day
- 6 am61°Fdew point 54°F
- 9 am68°Fdew point 55°F
- Noon73°Fdew point 54°F
- 3 pm74°Fdew point 54°F
- 6 pm70°Fdew point 54°F
- 9 pm67°Fdew point 55°F
NOAA hourly normals (local standard time) from Chicago Midway Airport (7 mi away); average wind 9 mph.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F15 of 30
- Beach dayshigh 80-95°F, under 0.05 in of rain, afternoon wind under 15 mph8 of 30
- Hot dayshigh 90°F or more2 of 30
- Muggy daysdaily mean dew point 65°F or more3 of 30
- Wet daysat least 0.01 in of rain or melted snow8 of 30
- Notable rainat least 0.10 in6 of 30
- Freezing nightslow 32°F or below0 of 30
- Snow on the groundsnow depth 1 in or more0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 3.3 in; a dry September brings about 1.9 in and a wet one about 4.2 in (25th and 75th percentiles). About 2 days bring half an inch or more, and about 1 an inch or more.
How September varies from year to year
- Warmest September, 1991-20202005: average high 81°F
- Coolest September1993: average high 69°F
- Wettest September2008: 10.8 in
- Driest September2009: 0.5 in
- Highest reading96°F (September 10, 2013)
- Lowest reading35°F (September 30, 1993)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 83°F | 77°F | 64°F |
| Normal low | 67°F | 59°F | 47°F |
| Wet days | 9 | 8 | 11 |
| Comfortable days | 7 | 15 | 11 |
| Daylight | 13.8 h | 12.5 h | 11.1 h |
Highs change by -6°F from August and -13°F into October.
Nearby alternatives in September
- Cooler: Sister Bay, WI232 mi · high 68°F · 10 wet days
How Chicago ranks in September
- Normal high251st warmest of 378 cities; 3rd of 8 in Illinois
- Wet days212th driest of 378
- Comfortable days83rd most of 342
What to pack for Chicago in September
- A rain jacket or umbrella – rain on about 8 days
Heating and cooling
September has 59 heating degree days and 144 cooling degree days (base 65°F), 3% of the year's total heating and cooling demand.
Questions
How hot is Chicago in September?
The normal high is 77°F and the normal low is 59°F. From 1991 to 2020 the hottest September reading was 96°F (September 10, 2013).
Does it rain a lot in Chicago in September?
About 8 days in September have at least 0.01 in of precipitation, and the normal total is 3.3 in. The wettest September in 1991-2020 was in 2008 (10.8 in); the driest was in 2009 (0.5 in).
Is September a good time to visit Chicago?
September ranks 2nd of 12 months on our comfort score for Chicago (67 out of 100). It has about 15 comfortable days and about 2 days at 90°F or hotter. The best months are May and September.
Where the numbers come from
- Temperature, rain, snowfall and snow depth: Chicago Midway Airport 3SW (USC00111577), 10 mi SW of the city center, 620 ft . NOAA normals and daily records, 1991-2020.
- Frost dates and humidity and wind by hour: Chicago Midway Airport (USW00014819), 6.9 mi SW of the city center, 612 ft . NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Chicago Midway Intl Arpt (725340-14819), 7.1 mi SW of the city center, 610 ft . Hourly observations, 1991-2020.
- Not available for this location: cloud cover (no station close enough or similar enough in elevation).