Illinois Weather Forecast
Illinois weather: 48°F, clear. Hourly forecast, 14-day outlook, UV, air quality and the best time to visit.
Summary
Illinois is a state in United States. Illinois is a US state with its capital at Springfield. It has a population of about 12.6 million. The capital is Springfield.
Right now it is 48°F (9°C) in Illinois with clear. It feels like 44°F. Today runs from 46°F to 74°F. Chance of precipitation is 0%. Sightseeing conditions score 8.7/10 - excellent - go now.
The best time to visit Illinois is 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 85°F, while January is the coldest with lows near 19°F.
The closest major airport is O'Hare International Airport (ORD), about 177 mi away. Nearby highlights include Starved Rock State Park, Lake Michigan, Gateway Arch National Park and Indiana Dunes National Park.
In plain terms. Today is slightly warmer than average for October. The forecast high of 74°F is 5°F above the 69°F typical for this month. The best window to be outside is roughly 12 PM to 3 PM, when temperature, rain chance and wind line up best. stargazing is the strongest bet in Illinois today at 10/10. 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.
Weather in Illinois right now
Source: Open-Meteo. Updated 11:17 AM, Oct 3 local time.
See the Illinois forecast by time range
Next 24 hours
Hour-by-hour temperature, precipitation chance and wind.
16-day forecast for Illinois
Daily highs and lows, precipitation and UV.
| Day | Conditions | High / Low | Precip | Wind | UV |
|---|---|---|---|---|---|
| Sat, Oct 3 | ☀️ Clear sky | 74° / 46° | 0% | 7 mph | 5 |
| Sun, Oct 4 | 🌤️ Mainly clear | 75° / 48° | 0% | 13 mph | 5 |
| Mon, Oct 5 | ☁️ Overcast | 74° / 50° | 0% | 9 mph | 5 |
| Tue, Oct 6 | ☀️ Clear sky | 78° / 51° | 0% | 11 mph | 5 |
| Wed, Oct 7 | ☁️ Overcast | 85° / 57° | 0% | 11 mph | 5 |
| Thu, Oct 8 | 🌤️ Mainly clear | 82° / 62° | 1% | 10 mph | 5 |
| Fri, Oct 9 | ☀️ Clear sky | 91° / 59° | 1% | 12 mph | 5 |
| Sat, Oct 10 | ☀️ Clear sky | 92° / 64° | 3% | 13 mph | 5 |
| Sun, Oct 11 | ☁️ Overcast | 78° / 64° | 15% | 15 mph | 3 |
| Mon, Oct 12 | 🌦️ Drizzle | 79° / 65° | 19% · 0,1 in | 11 mph | 3 |
| Tue, Oct 13 | 🌤️ Mainly clear | 79° / 56° | 12% | 11 mph | 5 |
| Wed, Oct 14 | ☀️ Clear sky | 81° / 57° | 8% | 14 mph | 5 |
| Thu, Oct 15 | ☀️ Clear sky | 71° / 49° | 14% | 9 mph | 5 |
| Fri, Oct 16 | 🌤️ Mainly clear | 66° / 47° | 13% | 12 mph | 5 |
| Sat, Oct 17 | ☁️ Overcast | 62° / 43° | 17% | 11 mph | 4 |
| Sun, Oct 18 | ☀️ Clear sky | -- / -- | 19% | -- | — |
Climate in Illinois 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 | 33° | 19° | 2,4 in | ★★☆☆☆ |
| February | 46° | 27° | 0,8 in | ★★★☆☆ |
| March | 60° | 39° | 3,5 in | ★★★☆☆ |
| April | 67° | 48° | 5,3 in | ★★★☆☆ |
| May | 74° | 56° | 3,9 in | ★★★★☆ |
| June | 83° | 66° | 4,6 in | ★★★★☆ |
| July | 85° | 69° | 5,1 in | ★★★★☆ |
| August | 83° | 67° | 3,0 in | ★★★★☆ |
| September | 82° | 63° | 1,3 in | ★★★★★ |
| October | 69° | 50° | 1,5 in | ★★★★☆ |
| November | 54° | 38° | 3,1 in | ★★★☆☆ |
| December | 43° | 29° | 2,4 in | ★★☆☆☆ |
Climate type: Continental. Source: Open-Meteo archive (ERA5).
Weather map for Illinois
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 Illinois
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 Illinois
Go in 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.
Weather by city in Illinois
1 cities mapped in this atlas
Weather by state park in Illinois
1 state and provincial parks mapped in this atlas
Weather by county in Illinois
1 counties mapped in this atlas
Weather by lake in Illinois
1 lakes mapped in this atlas
Explore Illinois
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 Illinois?
Illinois is a state in United States. Its coordinates are 39.7817, -89.6501. It lies in North America.
What is the weather like in Illinois right now?
It is currently 48°F (9°C) with clear. Humidity is 74% and wind is 4 mph.
When is the best time to visit Illinois?
August, September and October offer the most comfortable conditions in Illinois, which has a continental climate. January, February and December are usually the hardest months for outdoor plans.
What time zone is Illinois in?
Illinois observes America/Chicago (UTC-05:00). The local time is 11:17 AM.
How many people live in Illinois?
Illinois has a population of approximately 12.6 million.
What is the nearest airport to Illinois?
The closest airports are O'Hare International Airport (ORD), 177 mi away and Nashville International Airport (BNA), 300 mi away.
What are the top things to do in Illinois?
Popular options include Starved Rock State Park, Lake Michigan, Gateway Arch National Park and Indiana Dunes National Park.
What places are in Illinois?
Illinois covers 4 places in this atlas, including Chicago, Starved Rock State Park, Cook County and Lake Michigan.
Related articles
Data sources and methodology
| Place data | USPOTUS Atlas dataset (us-states) - 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 October 3, 2026 at 11:17 AM local time. Live blocks refresh every 15 minutes; climate averages monthly.
