Climate averages 1991–2020
Chicago weather
in October.
A mild, moderately wet month: the 6th warmest and the 7th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
October is a mild month in Chicago: daytime highs average 15.9°C and nights cool to about 9.2°C. By daytime temperature it is the 6th warmest of the 12 months.
Expect about 85 mm of rain on roughly 10 days, which makes October a moderately wet month (the 7th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 11 h 07 min on an average October day.
The nearest other city in this atlas is Cicero (9 km away). In October its highs average 16.3°C, about as warm as Chicago, with 85 mm of rain.
Among the 498 cities listed in the United States, Chicago ranks joint 421st of 498 for the warmest October highs and joint 300th of 498 for the driest October (rainfall, lowest first). The mean October high of those 498 cities is 21.4°C; Chicago is 5.5°C cooler than that mean.
From October to November, average highs fall by 7.5°C to 8.4°C, and monthly rainfall falls from 85 mm to 72 mm.
The annual picture
October 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
Chicago climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -0.7°C-7.4°C | -7.4°C | 62 | 9.1 | 9.510 h |
| February | 0.9°C-6.5°C | -6.5°C | 54 | 7.6 | 10.611 h |
| March | 6.0°C-1.6°C | -1.6°C | 71 | 10.3 | 11.912 h |
| April | 12.3°C4.4°C | 4.4°C | 114 | 12.4 | 13.313 h |
| May | 18.7°C10.9°C | 10.9°C | 110 | 12.4 | 14.515 h |
| June | 24.6°C17.2°C | 17.2°C | 102 | 12.1 | 15.215 h |
| July | 27.3°C20.2°C | 20.2°C | 92 | 11.5 | 14.915 h |
| August | 26.4°C19.7°C | 19.7°C | 95 | 10.9 | 13.914 h |
| September | 22.7°C15.8°C | 15.8°C | 75 | 8.8 | 12.513 h |
| October, selected | 15.9°C9.2°C | 9.2°C | 85 | 9.5 | 11.111 h |
| November | 8.4°C2.4°C | 2.4°C | 72 | 9.0 | 9.910 h |
| December | 2.2°C-3.5°C | -3.5°C | 61 | 8.7 | 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
October in nearby cities
- Cicero in OctoberUnited States · 9 kmHigh 16.3°C · Low 8.7°C · 85 mm rain
- Evanston in OctoberUnited States · 22 kmHigh 15.3°C · Low 9.8°C · 83 mm rain
- Hammond in OctoberUnited States · 32 kmHigh 16.2°C · Low 9.3°C · 83 mm rain
- Arlington Heights in OctoberUnited States · 38 kmHigh 15.8°C · Low 8.6°C · 79 mm rain
- Gary in OctoberUnited States · 38 kmHigh 16.0°C · Low 9.5°C · 83 mm rain
- Bolingbrook in OctoberUnited States · 39 kmHigh 16.3°C · Low 7.9°C · 79 mm rain
- Schaumburg in OctoberUnited States · 41 kmHigh 15.9°C · Low 7.7°C · 79 mm rain
- Naperville in OctoberUnited States · 42 kmHigh 16.2°C · Low 7.9°C · 80 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 Chicago) is explained once on the Chicago year overview and on the Sources, method and limits page.
Cicero lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.