Cook County Weather Forecast
Cook County weather: 69°F, clear. Hourly forecast, 14-day outlook, UV, air quality and the best time to visit.
Cook County weather in May
Weather map for Cook County
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Animated layers by Windy. For pin-level detail and nearby places, see the interactive map below.
Climate in Cook County month by month
Average high, average low and total rainfall, based on three years of reanalysis data.
| Month | Avg high | Avg low | Rainfall | Rating |
|---|---|---|---|---|
| January | 29° | 17° | 2,9 in | ★★☆☆☆ |
| February | 40° | 25° | 0,7 in | ★★★☆☆ |
| March | 51° | 34° | 4,1 in | ★★★☆☆ |
| April | 59° | 43° | 4,4 in | ★★★☆☆ |
| May | 67° | 51° | 2,7 in | ★★★★☆ |
| June | 79° | 64° | 5,0 in | ★★★★☆ |
| July | 82° | 68° | 5,0 in | ★★★★☆ |
| August | 79° | 66° | 3,1 in | ★★★★☆ |
| September | 75° | 61° | 3,6 in | ★★★★☆ |
| October | 64° | 50° | 3,1 in | ★★★★☆ |
| November | 50° | 38° | 2,7 in | ★★★☆☆ |
| December | 38° | 27° | 2,7 in | ★★☆☆☆ |
Climate type: Continental. Source: Open-Meteo archive (ERA5).
Best time to visit Cook County
Go in May, June, August, September and October. These months score highest on comfortable temperatures, low rainfall and useful daylight.
Hardest months: January, February and December - expect the least comfortable mix of heat, cold or rain.
What to pack, what to skip
- Lightweight, light-coloured clothing and a refillable water bottle
- Sunglasses, a brimmed hat and SPF 30+
- If your dates are flexible, avoid January, February and December - historically the least comfortable months here.
How Cook County compares with nearby places
Annual averages, and the difference against Cook County.
| Place | Distance | Avg temp | vs here | Annual rain |
|---|---|---|---|---|
| Area Code 312 | 0 mi | 52°F | about the same | 40 in |
| Chicago | 0 mi | 52°F | about the same | 40 in |
| The Loop | 0 mi | 52°F | about the same | 40 in |
| ZIP Code 60601 | 1 mi | 52°F | about the same | 40 in |
| Wicker Park | 3 mi | 52°F | about the same | 38 in |
See the Cook County forecast by time range
Cook County weather - more answers
Explore Cook County
Every topic we hold for this place, and the same topic for the places around it.
Weather for related places
Frequently asked questions
Where is Cook County?
Cook County is a county in Illinois. Its coordinates are 41.8781, -87.6298. It lies in North America.
What is the weather like in Cook County right now?
It is currently 69°F (20°C) with clear. Humidity is 81% and wind is 5 mph.
When is the best time to visit Cook County?
May, June, August, September and October offer the most comfortable conditions in Cook County, which has a continental climate. January, February and December are usually the hardest months for outdoor plans.
What time zone is Cook County in?
Cook County observes America/Chicago (UTC-05:00). The local time is 8:53 AM.
How many people live in Cook County?
Cook County has a population of approximately 5.1 million.
What is the nearest airport to Cook County?
The closest airports are O'Hare International Airport (ORD), 16 mi away.
What are the top things to do in Cook County?
Popular options include Indiana Dunes National Park, Starved Rock State Park and Lake Michigan.
Related articles
Data sources and methodology
| Place data | USPOTUS Atlas dataset (us-counties) - coordinates, hierarchy and facts. |
|---|---|
| Forecast and observations | Open-Meteo (ECMWF and national models). |
| Air quality and pollen | Copernicus CAMS via Open-Meteo. US AQI scale. |
| Climate averages | ERA5 reanalysis via the Open-Meteo archive, aggregated over 3 years. |
| Official alerts | US National Weather Service. |
| Method | Scores, comparisons and advice on this page are computed from the inputs above. Distances are straight-line. Nothing is estimated where data is missing - the block is simply not shown. |
Last updated August 22, 2026 at 8:53 AM local time. Live blocks refresh every 15 minutes; climate averages monthly.
