Cook County Weather Forecast
Cook County weather: 63°F, clear. Hourly forecast, 14-day outlook, UV, air quality and the best time to visit.
Summary
Cook County is a county in Illinois. Cook County is a county in the United States. It has a population of about 5.1 million.
Right now it is 63°F (17°C) in Cook County with clear. It feels like 58°F. Today runs from 51°F to 70°F. Chance of precipitation is 4%. Sightseeing conditions score 9.2/10 - excellent - go now.
The best time to visit Cook County is May, June, August, September and October. The climate is continental. January, February and December tend to be the least comfortable months. July is the warmest month with average highs near 82°F, while January is the coldest with lows near 17°F.
The closest major airport is O'Hare International Airport (ORD), about 16 mi away. Nearby highlights include Indiana Dunes National Park, Starved Rock State Park and Lake Michigan.
In plain terms. Today is slightly cooler than average for September. The forecast high of 70°F is 5.4°F below the 75°F typical for this month. The best window to be outside is roughly 1 PM to 4 PM, when temperature, rain chance and wind line up best. stargazing is the strongest bet in Cook County today at 9.4/10. No weather-related travel disruption is expected today. Roads and airports should run normally.
Compiled from this page's own data: atlas facts plus live Open-Meteo readings.
Active alerts for Cook County
Beach Hazards Statement issued September 14 at 9:22PM CDT until September 15 at 7:00AM CDT by NWS Chicago IL
Issued by NWS Chicago IL
Weather in Cook County right now
Source: Open-Meteo. Updated 1:00 AM, Sep 15 local time.
See the Cook County forecast by time range
Next 24 hours
Hour-by-hour temperature, precipitation chance and wind.
16-day forecast for Cook County
Daily highs and lows, precipitation and UV.
| Day | Conditions | High / Low | Precip | Wind | UV |
|---|---|---|---|---|---|
| Mon, Sep 14 | ☁️ Overcast | 70° / 51° | 4% | 12 mph | 6 |
| Tue, Sep 15 | 🌦️ Light rain | 75° / 62° | 50% · 0,1 in | 14 mph | 5 |
| Wed, Sep 16 | 🌦️ Light rain | 70° / 63° | 48% · 0,1 in | 12 mph | 3 |
| Thu, Sep 17 | 🌦️ Light showers | 74° / 64° | 64% · 0,5 in | 8 mph | 4 |
| Fri, Sep 18 | 🌦️ Light drizzle | 71° / 66° | 18% · 0,0 in | 12 mph | 3 |
| Sat, Sep 19 | 🌦️ Drizzle | 88° / 66° | 57% · 0,1 in | 12 mph | 6 |
| Sun, Sep 20 | 🌧️ Showers | 71° / 60° | 57% · 1,2 in | 17 mph | 1 |
| Mon, Sep 21 | 🌧️ Showers | 62° / 59° | 25% · 0,8 in | 17 mph | 1 |
| Tue, Sep 22 | 🌧️ Showers | 59° / 57° | 9% · 0,6 in | 16 mph | 1 |
| Wed, Sep 23 | 🌦️ Light drizzle | 64° / 56° | 10% · 0,0 in | 10 mph | 3 |
| Thu, Sep 24 | 🌦️ Light drizzle | 67° / 58° | 8% · 0,0 in | 12 mph | 4 |
| Fri, Sep 25 | ☁️ Overcast | 66° / 63° | 13% | 10 mph | 3 |
| Sat, Sep 26 | 🌦️ Light drizzle | 71° / 63° | 11% · 0,0 in | 7 mph | 5 |
| Sun, Sep 27 | 🌦️ Light drizzle | 73° / 63° | 10% · 0,0 in | 8 mph | 5 |
| Mon, Sep 28 | ☁️ Overcast | 68° / 62° | 13% | 13 mph | 2 |
| Tue, Sep 29 | 🌦️ Light drizzle | 63° / 59° | 23% · 0,0 in | 11 mph | 4 |
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 | 80° | 67° | 3,4 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).
Weather map for Cook County
Animated model layers. Pick a layer to load it.
Animated layers by Windy. For pin-level detail and nearby places, see the interactive map below.
Air quality and pollen in Cook County
Air quality: Open-Meteo (CAMS). US AQI scale.
Sun, twilight and moon
Golden and blue hour are the standard photographic approximation around sunrise and sunset.
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.
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 63°F (17°C) with clear. Humidity is 67% and wind is 12 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 1:00 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 September 15, 2026 at 1:00 AM local time. Live blocks refresh every 15 minutes; climate averages monthly.
