Chicago weather in October
In October, Chicago has daytime highs averaging 16 °C, nights around 9.5 °C, with 9.3 wet days. Figures are 1991–2020 climate normals.
- 16.4°C Average high
- 9.5°C Average low
- 9.3days Wet days
- 86mm Rainfall
- 11h Daylight
Daily temperatures through October
How October develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 October | 19.2 °C | 12.0 °C | 29 % |
| 11–20 October | 16.4 °C | 9.4 °C | 28 % |
| 21–31 October | 13.9 °C | 7.6 °C | 33 % |
- Average highs fall from 19.2 °C early in October to 13.9 °C by the end of it.
What to expect
| Measure | Typical October | Share of the month |
|---|---|---|
| Days above 25 °C | 1.4 of 31 | 5 % |
| Days above 30 °C | 0 of 31 | 0 % |
| Days below 0 °C | 0.1 of 31 | 0 % |
| Days with more than 1 mm rain | 9.3 of 31 | 30 % |
Conditions in October
| Measure | Average |
|---|---|
| Mean temperature | 12 °C |
| Record high (1991–2020) | 30 °C |
| Record low (1991–2020) | -1.1 °C |
| Relative humidity | 70 % |
| Wind speed | 23 km/h |
| Cloud cover | 56 % |
Where Chicago ranks in October
| Ranking | Position | Value |
|---|---|---|
| The coolest places in North America in October | 44thof 50 | 16 °C |
October compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| August | 26.9 °C | 98 mm | 50 % |
| September | 23.2 °C | 79 mm | 48 % |
| October | 16.4 °C | 86 mm | 56 % |
| November | 8.8 °C | 72 mm | 63 % |
| December | 2.6 °C | 61 mm | 70 % |
See all twelve months for Chicago
- October is the 6th warmest month here.
- It is the 7th driest month of the year.
- It ranks 4th for least cloud cover.
- Days last about 11 hours from sunrise to sunset.
- It rains on 9.3 of 31 days — 30 % of the month.
- Nights are about 6.8 °C cooler than the middle of the day.
- The hottest October day on record since 1991 reached 30 °C, 13 °C above the usual daytime high.
QuestionsOctober in Chicago, answered
How warm is Chicago in October?
Daily highs average 16 °C and nights fall to about 9.5 °C, a spread of 6.8 °C between afternoon and dawn. That makes October the 6th warmest month of the year here.
Does it rain much in Chicago in October?
October averages 86 mm of rain, spread over about 9 of the 31 days — 30 % of the month. Cloud cover averages 56 % of the sky.
How long are the days in October?
Chicago averages 11 hours between sunrise and sunset in October. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.