Chicago, IL climate: monthly averages and frost dates
Chicago, IL has cold winters and warm summers by this site's scale, with moderate annual precipitation. The figures are the 1991–2020 climate normals for NOAA station USW00094846 (CHICAGO OHARE INTL AP), 17 mi (27 km) in a straight line from the city's center point (US Census).
- Warmest month high
- 84.5°F
- July
- Coldest month mean
- 25.2°F
- January
- Precipitation
- 37.9 in
- per year
- Snowfall
- 38.4 in
- per year
- Median last frost
- April 16
- 32°F, spring
- Median first frost
- October 28
- 32°F, autumn
Monthly averages in Chicago
| Month | High °F | Low °F | Mean °F | Precip. in | Snow in | Days ≥0.01 in | Days ≥90°F | Nights ≤32°F |
|---|---|---|---|---|---|---|---|---|
| January | 31.6 | 18.8 | 25.2 | 1.99 | 11.3 | 11.0 | 0.0 | 28.1 |
| February | 35.7 | 21.8 | 28.8 | 1.97 | 10.7 | 9.4 | 0.0 | 24.4 |
| March | 47.0 | 31.0 | 39.0 | 2.45 | 5.5 | 10.8 | 0.0 | 19.9 |
| April | 59.0 | 40.3 | 49.7 | 3.75 | 1.3 | 12.3 | 0.0 | 6.0 |
| May | 70.5 | 50.6 | 60.6 | 4.49 | 0.0 | 12.5 | 0.8 | 0.2 |
| June | 80.4 | 60.8 | 70.6 | 4.10 | 0.0 | 11.1 | 4.1 | 0.0 |
| July | 84.5 | 66.4 | 75.4 | 3.71 | 0.0 | 9.7 | 6.5 | 0.0 |
| August | 82.5 | 65.1 | 73.8 | 4.25 | 0.0 | 9.4 | 3.7 | 0.0 |
| September | 75.5 | 57.1 | 66.3 | 3.19 | 0.0 | 8.5 | 1.6 | 0.1 |
| October | 62.7 | 45.4 | 54.0 | 3.43 | 0.2 | 10.5 | 0.0 | 2.7 |
| November | 48.4 | 34.1 | 41.3 | 2.42 | 1.8 | 10.0 | 0.0 | 14.5 |
| December | 36.6 | 24.4 | 30.5 | 2.11 | 7.6 | 10.6 | 0.0 | 25.4 |
| Year | 59.5 | 43.0 | 51.2 | 37.86 | 38.4 | 125.8 | 16.7 | 121.3 |
How cold is winter in Chicago?
Winters in Chicago are cold by this site's scale (coldest-month mean 20 to under 32°F). The coldest month is January, with a mean temperature of 25.2°F (−3.8°C), a normal daily high of 31.6°F (−0.2°C) and a normal daily low of 18.8°F (−7.3°C).
The station averages 121.3 nights a year at or below 32°F and 43.4 days when the high stays at or below 32°F.
The normal daily low is at or below freezing in December to March.
How hot is summer in Chicago?
Summers in Chicago are warm by this site's scale (hottest-month high 80 to under 90°F). July has the highest normal daily high, 84.5°F (29.2°C), with nights averaging 66.4°F (19.1°C).
The high reaches 90°F or more on 16.7 days in a normal year.
What is the wettest month in Chicago?
Chicago gets 37.86 in (962 mm) of precipitation in a normal year, which this site classes as moderate (20 to under 40 in a year). The wettest month is May with 4.49 in (114 mm); the driest is February with 1.97 in (50 mm).
Measurable precipitation (0.01 in or more) falls on 125.8 days a year.
Does it snow in Chicago?
Normal annual snowfall in Chicago is 38.4 in (98 cm), which this site classes as heavy (36 to under 72 in a year).
January is the snowiest month, with 11.3 in (29 cm).
A day with 1.0 in or more of snowfall comes 11.4 times a year on average.
Which months are mild in Chicago?
5 months in Chicago meet this site's comfort thresholds (normal high 65–85°F, low 45°F or higher, fewer than 10 days with 0.10 in or more of precipitation): May to September.
Thresholds and their limits: methodology.
Frost dates and growing season in Chicago
In Chicago the median last spring night at or below 32°F is April 16, and the median first autumn one is October 28 (NOAA P50 dates). NOAA's median length of the freeze-free season is 193 days. NOAA takes that median over each year's own season, so it need not equal the 195 days between the two median dates.
There is still a 10% chance of a 32°F night on or after May 1, and a 10% chance that the first one has come by October 15.
The chance that the last spring 32°F night comes on or after April 3 is 90%.
For a hard freeze (28°F or lower) the median dates are April 5 in spring and November 7 in autumn.
| Chance | Last spring 32°F night on or after | First autumn 32°F night by | Freeze-free season, days |
|---|---|---|---|
| 10% | May 1 | October 15 | 213 |
| 20% | April 26 | October 20 | 206 |
| 30% | April 22 | October 24 | 201 |
| 40% | April 19 | October 26 | 197 |
| 50% | April 16 | October 28 | 193 |
| 60% | April 14 | October 31 | 189 |
| 70% | April 11 | November 3 | 185 |
| 80% | April 8 | November 5 | 180 |
| 90% | April 3 | November 11 | 173 |
| Threshold | Median last date (spring) | Median first date (autumn or winter) | Median season, days |
|---|---|---|---|
| 36°F | April 29 | October 18 | 170 |
| 32°F | April 16 | October 28 | 193 |
| 28°F | April 5 | November 7 | 217 |
| 24°F | March 24 | November 17 | 238 |
| 20°F | March 13 | November 26 | 258 |
| 16°F | March 5 | December 3 | 275 |
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 100% | 100% | 100% | 93% | 10% | 0% | 0% | 0% | 0% | 62% | 100% | 100% |
Nearby and similar places
Of the places on this site, the closest to Chicago by station distance are Indianapolis, IN at 180 mi (290 km), Detroit, MI at 236 mi (381 km) and Minneapolis, MN at 332 mi (535 km).
Among places whose winter, summer and precipitation words are each within one band of Chicago's (winter: cold, summer: warm, precipitation: moderate), the closest monthly temperature and precipitation patterns are Detroit, MI, Burlington, VT and Kansas City, MO.
Compared with Indianapolis, IN, Chicago's peak-month normal high is 0.7°F (0.4°C) lower, its coldest-month mean is 3.3°F (1.8°C) lower, and its annual precipitation is 5.77 in less.
| Place | Listed as | Station distance | Coldest mean °F | Warmest high °F | Precip. in/yr | Snow in/yr | Last frost |
|---|---|---|---|---|---|---|---|
| Chicago, IL | this page | – | 25.2 | 84.5 | 37.9 | 38.4 | April 16 |
| Indianapolis, IN | nearby | 180 mi (290 km) | 28.5 | 85.2 | 43.6 | 25.5 | April 15 |
| Detroit, MI | nearby, similar | 236 mi (381 km) | 25.8 | 83.7 | 34.3 | 45.0 | April 20 |
| Minneapolis, MN | nearby | 332 mi (535 km) | 16.2 | 83.4 | 31.6 | 51.2 | April 23 |
| Burlington, VT | similar | 762 mi (1,227 km) | 20.9 | 82.4 | 37.5 | 87.5 | April 29 |
| Kansas City, MO | similar | 402 mi (647 km) | 29.0 | 88.3 | 39.3 | 18.2 | April 13 |
How nearby and similar places are chosen: methodology.
Source and station
The data for Chicago come from NOAA station CHICAGO OHARE INTL AP, IL US (USW00094846) at 41.9950, -87.9336, elevation 658 ft (201 m). It lies 17 mi (27 km) in a straight line from the center point of Chicago city, the “internal point” in the US Census 2024 Gazetteer.
Each monthly normal used here rests on at least 25 years of data from 1991–2020 (NOAA's per-field year counts).
NOAA completeness flags on the monthly fields used here:
- S: Standard: meets WMO standards for data availability for 24 or more years.
Cite the data as:
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). Station USW00094846 (CHICAGO OHARE INTL AP, IL US). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/wck8-er13. Accessed 2026-10-09.
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020). Station USW00094846 (CHICAGO OHARE INTL AP, IL US). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/4ek7-fk11. Accessed 2026-10-09.
Files used: monthly normals CSV, annual/seasonal normals CSV (retrieved 2026-10-09). The values on this page as JSON: /us/il/chicago/data.json.