Chicago Weather for Cyclists: Temperatures, Wind and Alert Levels

Chicago weather decides when you ride and how you dress. The numbers below come from the National Weather Service, which publishes the 1991-2020 climate normals for O’Hare and the alert levels that apply to the Chicago area¹. This guide is part of Plan a Ride.

Temperatures by month

The normals cover 1991 to 2020¹. They give a clear season: a long cold stretch, a short warm one, and shoulder months that reward a jacket.

Month	Average high	Average low	Precipitation	Snowfall
January	31.6°F	18.8°F	1.99 in	11.3 in1
February	35.7°F	21.8°F	1.97 in	10.7 in1
March	47.0°F	31.0°F	2.45 in	5.5 in1
April	59.0°F	40.3°F	3.75 in	1.3 in1
May	70.5°F	50.6°F	4.49 in	trace1
June	80.4°F	60.8°F	4.10 in	0.0 in1
July	84.5°F	66.4°F	3.71 in	0.0 in1
August	82.5°F	65.1°F	4.25 in	0.0 in1
September	75.5°F	57.1°F	3.19 in	0.0 in1
October	62.7°F	45.4°F	3.43 in	0.2 in1
November	48.4°F	34.1°F	2.42 in	1.8 in1
December	36.6°F	24.4°F	2.11 in	7.6 in1

The year averages 59.5°F for highs, 43.0°F for lows and 37.86 inches of precipitation¹.

The riding season

April through October is the core season. Average highs run from 59.0°F in April to 84.5°F in July, and back to 62.7°F in October¹. May is the month where highs first reach 70.5°F¹. Rain is steady rather than seasonal: May, June and August each average more than four inches¹.

Days at or above 90°F are few. There are 16.7 a year, and July has the most at 6.5¹. June has 4.1 and August has 3.7¹. The Weather Service’s heat index measures how hot it feels when relative humidity is added to the air temperature⁵. Its Chicago heat alert begins when the heat index is expected to reach or exceed 105°². Ride early on those days.

Cold, snow and ice

Winter is the limit, not the exception. Highs stay at or below 32°F on 43.4 days a year¹. January has 16.5 of them and February 11.2¹. Lows reach 32°F or colder on 121.3 days¹. Lows fall to 0°F or colder on 6.5 days a year, mostly in January and February¹.

Snow totals 38.4 inches a year, with 11.3 in January and 10.7 in February¹. April still averages 1.3 inches, and October has a trace of 0.2 inches¹. The Weather Service names “black ice” among short-term hazards, along with fog and sudden strong winds². Frost advisories apply in the growing season².

Wind chill

Wind chill is how cold people feel outside, and it applies to people and animals only⁴. At 0°F with a 15 mph wind, the wind chill is -19°F, and exposed skin can freeze in 30 minutes⁴. The index is defined only for temperatures at or below 50°F and wind speeds above 3 mph⁴. Bright sunshine can lift the wind chill by 10°F to 18°F⁴.

Frostbite needs air below freezing⁴. Above freezing, the risk is hypothermia from exposure to cold⁴. The Chicago office issues a Cold Weather Advisory for wind chills of -20 to -29°, and an Extreme Cold Warning for -30° or colder². Do not ride at either level. For cold-season gear and routes, read the winter cycling guide.

Wind

The Weather Service publishes no cycling wind limit. It does publish alert levels. NWS Chicago’s Wind alert is sustained winds of 30 to 39 mph, or gusts of 45 mph or stronger, lasting at least one hour². High Wind is 40 mph sustained for at least one hour, or gusts of 58 mph or more². A severe thunderstorm is one capable of 50 knot (58 mph) winds².

For a sense of the ordinary, the O’Hare report for September 2026 recorded an average wind speed of 8.1 mph³. The highest wind that month was 24 mph, and the highest gust was 32 mph³. That gust sits below the Wind alert level. Treat any day at or above that level as a day off the bike.

Visibility and the lake

Dense fog means visibility of a quarter mile or less across a wide area². Ride with lights when that is forecast. The Weather Service also issues a Beach Hazards Statement when hazardous conditions are expected at beach and shore areas and adjacent surf zone waters². The Lakefront Trail runs beside that shoreline, so check it before a lakefront ride.

What to check before you ride

Use three numbers: the forecast wind speed and gust, the wind chill if it is 50°F or lower, and the heat index in summer⁴⁵. Compare them with the thresholds above. For the best months by use, read best time to bike in Chicago, and for a first ride in the city, see biking in Chicago for the first time.