Chicago, Illinois climate: Normal weather by month, frost dates and records
Chicago's normal year runs from 19°F January nights to 85°F July afternoons, with 37.9 inches of precipitation and 38 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 10.7°C, January lows of −7°C, July highs of 29°C, 962 mm of precipitation a year.
- 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
On October 23, the normal high in Chicago is 60°F and the normal low 43°F, and the chance of measurable rain or snow is 34%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Chicago.
- 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.
What is the weather like in Chicago each month?
July is the warmest month, with normal highs of 85°F; January the coldest, with normal lows of 19°F. The most precipitation falls in May (4.49 in), the least in February (1.97 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 32°F | 19°F | 25.2°F | 1.99 | 11.3 | 11 | <1 | 28 | 9 h 30 min |
| February | 36°F | 22°F | 28.8°F | 1.97 | 10.7 | 9 | <1 | 24 | 10 h 30 min |
| March | 47°F | 31°F | 39.0°F | 2.45 | 5.5 | 11 | <1 | 20 | 11 h 50 min |
| April | 59°F | 40°F | 49.7°F | 3.75 | 1.3 | 12 | <1 | 6 | 13 h 20 min |
| May | 71°F | 51°F | 60.6°F | 4.49 | 0.0 | 13 | 1 | <1 | 14 h 30 min |
| June | 80°F | 61°F | 70.6°F | 4.10 | 0.0 | 11 | 4 | <1 | 15 h 10 min |
| July | 85°F | 66°F | 75.4°F | 3.71 | 0.0 | 10 | 7 | <1 | 15 h |
| August | 83°F | 65°F | 73.8°F | 4.25 | 0.0 | 9 | 4 | <1 | 14 h |
| September | 76°F | 57°F | 66.3°F | 3.19 | 0.0 | 9 | 2 | <1 | 12 h 30 min |
| October | 63°F | 45°F | 54.0°F | 3.43 | 0.2 | 11 | <1 | 3 | 11 h 10 min |
| November | 48°F | 34°F | 41.3°F | 2.42 | 1.8 | 10 | <1 | 15 | 9 h 50 min |
| December | 37°F | 24°F | 30.5°F | 2.11 | 7.6 | 11 | <1 | 25 | 9 h 10 min |
| Year (annual) | 60°F | 43°F | 51.2°F | 37.86 | 38.4 | 126 | 17 | 121 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 0°C | −7°C | −3.8°C | 51 mm | 29 cm |
| February | 2°C | −6°C | −1.8°C | 50 mm | 27 cm |
| March | 8°C | −1°C | 3.9°C | 62 mm | 14 cm |
| April | 15°C | 5°C | 9.8°C | 95 mm | 3 cm |
| May | 21°C | 10°C | 15.9°C | 114 mm | 0 cm |
| June | 27°C | 16°C | 21.4°C | 104 mm | 0 cm |
| July | 29°C | 19°C | 24.1°C | 94 mm | 0 cm |
| August | 28°C | 18°C | 23.2°C | 108 mm | 0 cm |
| September | 24°C | 14°C | 19.1°C | 81 mm | 0 cm |
| October | 17°C | 7°C | 12.2°C | 87 mm | 1 cm |
| November | 9°C | 1°C | 5.2°C | 61 mm | 5 cm |
| December | 3°C | −4°C | −0.8°C | 54 mm | 19 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094846; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Chicago?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, September has the fewest days with rain (9).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094846.
When is the last frost in Chicago?
In Chicago, the last spring frost (32°F) comes after April 16 in half of years and after May 1 in one year in ten; the first autumn frost comes before October 28 in half of years and before October 15 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 161 year in 10 after May 1; 9 in 10 after April 3
- First autumn frost, half of years before
- October 281 year in 10 before October 15; 9 in 10 before November 11
NOAA puts the median frost-free season at 193 days, and the season without a hard freeze (28°F) at 217 days.
A hard freeze (28°F) comes after April 5 in half of springs and before November 7 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Chicago in zones 6a to 6b across its 56 ZIP code areas (6a in 60617, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, Chicago's NOAA station is in zone 6a: the coldest night of a typical year reaches −8°F (30 complete years).
Frost dates for every NOAA station in Illinois · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00094846; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
What hardiness zone is each Chicago ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Chicago's 56 ZIP code areas run from zone 6a to 6b: 43 in 6a and 13 in 6b. Each ZIP's frost dates are in the frost tool.
| ZIP code | Zone | Land in Chicago |
|---|---|---|
| 60018 | 6a | 20.4 km² |
| 60106 | 6a | 6.8 km² |
| 60601 | 6b | 1.0 km² |
| 60605 | 6b | 3.7 km² |
| 60607 | 6b | 6.0 km² |
| 60608 | 6a | 16.2 km² |
| 60609 | 6a | 20.1 km² |
| 60610 | 6b | 2.9 km² |
| 60611 | 6b | 2.0 km² |
| 60612 | 6a | 9.6 km² |
| 60613 | 6b | 6.0 km² |
| 60614 | 6b | 8.3 km² |
| 60615 | 6b | 5.7 km² |
| 60616 | 6b | 9.8 km² |
| 60617 | 6a | 35.4 km² |
| 60618 | 6a | 12.9 km² |
| 60619 | 6a | 15.9 km² |
| 60620 | 6a | 17.8 km² |
| 60621 | 6a | 9.7 km² |
| 60622 | 6a | 6.5 km² |
| 60623 | 6a | 13.9 km² |
| 60624 | 6a | 9.2 km² |
| 60625 | 6a | 9.8 km² |
| 60626 | 6a | 4.5 km² |
| 60628 | 6a | 28.4 km² |
| 60629 | 6a | 17.9 km² |
| 60630 | 6a | 12.3 km² |
| 60631 | 6a | 9.5 km² |
| 60632 | 6a | 19.3 km² |
| 60633 | 6a | 20.4 km² |
| 60634 | 6a | 18.1 km² |
| 60636 | 6a | 10.1 km² |
| 60637 | 6a | 11.7 km² |
| 60638 | 6a | 15.5 km² |
| 60639 | 6a | 12.8 km² |
| 60640 | 6a | 6.1 km² |
| 60641 | 6a | 10.4 km² |
| 60642 | 6a | 4.3 km² |
| 60643 | 6a | 19.1 km² |
| 60644 | 6a | 9.1 km² |
| 60645 | 6a | 5.8 km² |
| 60646 | 6a | 11.5 km² |
| 60647 | 6a | 10.3 km² |
| 60649 | 6b | 9.4 km² |
| 60651 | 6a | 9.0 km² |
| 60652 | 6a | 12.5 km² |
| 60653 | 6b | 6.1 km² |
| 60654 | 6b | 1.4 km² |
| 60655 | 6a | 10.4 km² |
| 60656 | 6a | 8.1 km² |
| 60657 | 6a | 5.6 km² |
| 60659 | 6a | 6.1 km² |
| 60660 | 6a | 3.3 km² |
| 60661 | 6b | 0.8 km² |
| 60707 | 6a | 4.3 km² |
| 60827 | 6a | 4.2 km² |
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Chicago?
In a normal year in Chicago, 17 days a year reach 90°F, 121 nights fall to 32°F or colder and 126 days bring measurable precipitation.
- Days at 90°F or more
- 17a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 121a normal year
- Days that stay below freezing
- 43high of 32°F or less
- Days with 0.01 inch of precipitation
- 126a normal year
- Days with 1 inch of snow or more
- 11a normal year
The highest temperature in Chicago's official record (kept by the National Weather Service since 1872) is 105°F, on July 24, 1934; the lowest is −27°F, on January 20, 1985.
The wettest calendar year on that record is 2008, with 50.86 in; the snowiest season is 1978–79, with 89.7 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00094846; records: ACIS (NOAA Regional Climate Centers), NWS threaded record ORDthr. Records use complete months only; a month missing more than three days is left out.
How humid and windy is Chicago, and how clear are its skies?
The summer (June-August) dew point averages 61°F. The muggiest month is July, with an average dew point of 62°F; the driest air comes in January (18°F). March is the windiest month (11.1 mph on average), and August has the most clear or nearly clear hours (44%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 18°F | 73% | 64% | 10.5 mph | 30% | 49% |
| February | 23°F | 69% | 57% | 10.9 mph | 28% | 47% |
| March | 32°F | 63% | 49% | 11.1 mph | 30% | 41% |
| April | 40°F | 60% | 47% | 10.5 mph | 32% | 37% |
| May | 52°F | 64% | 50% | 9.1 mph | 36% | 28% |
| June | 61°F | 64% | 49% | 8.4 mph | 40% | 18% |
| July | 62°F | 66% | 50% | 7.8 mph | 38% | 18% |
| August | 60°F | 69% | 52% | 8.0 mph | 44% | 18% |
| September | 49°F | 68% | 51% | 9.0 mph | 42% | 24% |
| October | 37°F | 68% | 55% | 10.4 mph | 33% | 40% |
| November | 27°F | 73% | 63% | 10.4 mph | 28% | 48% |
| December | 20°F | 75% | 67% | 10.6 mph | 28% | 51% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00094846. Monthly averages of all hours; afternoon humidity at 3 p.m. local standard time; sky as the share of hours NOAA's observations rate clear or few clouds (a dash where NOAA publishes no sky value).
How sunny is Chicago?
Over a year 72% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Chicago, 3.8 kWh per square metre a day. July is the sunniest month (80%) and January the cloudiest (59%). Among the 459 U.S. places of 50,000 or more, that ranks tied 385th (with 30 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 59% | 1.6 |
| February | 63% | 2.5 |
| March | 67% | 3.6 |
| April | 69% | 4.7 |
| May | 70% | 5.4 |
| June | 77% | 6.1 |
| July | 80% | 6.2 |
| August | 79% | 5.3 |
| September | 79% | 4.4 |
| October | 70% | 2.9 |
| November | 66% | 1.9 |
| December | 59% | 1.4 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Chicago need?
A normal year in Chicago brings 5,974 heating degree days, 11% more than the median U.S. place (5,373), and 1,003 cooling degree days, 11% more than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,331 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,234 | 0 |
| February | 1,015 | 0 |
| March | 808 | 2 |
| April | 468 | 8 |
| May | 198 | 60 |
| June | 31 | 199 |
| July | 2 | 326 |
| August | 4 | 277 |
| September | 77 | 116 |
| October | 355 | 15 |
| November | 713 | 0 |
| December | 1,069 | 0 |
| Year (annual) | 5,974 | 1,003 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00094846. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Chicago been warmer than normal lately?
2025 averaged 52.1°F, 0.9°F above the 1991-2020 normal of 51.2°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 53.3°F | +2.1°F | 30.15 | 47.2 |
| 2022 | 51.3°F | +0.1°F | 31.99 | 35.2 |
| 2023 | 54.0°F | +2.8°F | 33.73 | 19.8 |
| 2024 | 55.0°F | +3.8°F | 34.92 | 23.6 |
| 2025 | 52.1°F | +0.9°F | 29.79 | 32.2 |
Over 71 complete years from 1948 to 2025, the station's annual mean temperature rose at a fitted 4.1°F per century (+0.23°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00094846; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Chicago's climate compare?
Chicago is warmer than 59 of the other 143 places with their own NOAA record in Illinois, and wetter than 29. Across the 7,247 U.S. stations with normals, its annual mean of 51.2°F is warmer than 46%.
In the Köppen classification computed from these normals, Chicago is Dfa: continental, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Chicago share this climate record?
22 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Des Plaines, ILalso near: Wheeling (6 mi, 50.8°F a year); Chicago Botanic Garden (9 mi, 49.6°F a year)58,832 people · 3 mi NE
- Elmhurst, IL46,108 people · 7 mi S
- Park Ridge, IL38,445 people · 5 mi E
- Addison, IL35,728 people · 6 mi SW
- Elk Grove Village, IL31,802 people · 3 mi W
- Niles, IL29,918 people · 7 mi E
- Melrose Park, IL23,999 people · 7 mi SE
- Elmwood Park, IL23,698 people · 8 mi SE
- Bensenville, IL18,629 people · 3 mi S
- Bellwood, IL18,132 people · 8 mi S
- Franklin Park, IL18,110 people · 5 mi SE
- Norridge, IL14,817 people · 6 mi E
- Wood Dale, IL13,983 people · 3 mi SW
- Northlake, IL12,433 people · 6 mi S
- Schiller Park, IL11,325 people · 4 mi SE
- River Grove, IL10,424 people · 7 mi SE
- Itasca, IL9,506 people · 5 mi W
- Harwood Heights, IL8,755 people · 7 mi E
- Hillside, IL8,031 people · 9 mi S
- Berkeley, IL5,155 people · 7 mi S
- Stone Park, IL4,473 people · 7 mi SE
- Rosemont, IL3,822 people · 3 mi E
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Chicago's other NOAA stations record?
3 more NOAA stations keep 1991-2020 normals in or near Chicago. This page uses Chicago O'Hare International Airport; the others differ by site and elevation, and the linked ones have pages of their own:
| Station | From the center | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Chicago Botanic Garden USC00111497 | 22 mi N | 630 ft | 49.6°F | 16°F | 84°F | 39.5 | 34 | April 26 |
| Chicago Midway Airport USW00014819 | 5 mi SW | 612 ft | 52.1°F | 19°F | 85°F | 34.4 | – | April 11 |
| Chicago Northerly Island USC00111550 | 4 mi E | 583 ft | 50.8°F | 20°F | 81°F | – | – | April 10 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Chicago's climate
What is the coldest month in Chicago?
January, with a normal high of 32°F and a normal low of 19°F. The warmest is July (85°F by day, 66°F at night).
Does it snow in Chicago?
Yes: 38 inches in a normal year, falling on 28 days with 0.1 inch or more, the most in January (11.3 inches).
What is the rainiest month in Chicago?
May, with 4.49 in of precipitation in a normal year; the driest is February with 1.97 in.
What plant hardiness zone is Chicago in?
The USDA's 2023 map puts Chicago in zones 6a to 6b across its 56 ZIP code areas (6a in 60617, the largest). By the same method at Chicago's NOAA station, the coldest night of a typical year reaches −8°F (30 years, 1991-2020): zone 6a.
How late can frost come in Chicago?
In half of years the last 32°F night comes after April 16; in one year in ten it comes after May 1. Waiting until May 1 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Chicago in OctoberThis month day by day, its records and recent years
- Illinois climateThe statewide normals and every place in the state
- Wheeling, IL9 miles from this station, 50.8°F a year
- Chicago Botanic Garden, IL12 miles from this station, 49.6°F a year
- Streamwood, IL13 miles from this station, 49.6°F a year
- Barrington, IL14 miles from this station, 48.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made