Illinois Weather Forecast
Illinois weather: 69°F, clear. Hourly forecast, 14-day outlook, UV, air quality and the best time to visit.
14-day forecast for Illinois
Daily highs and lows, precipitation and UV.
| Day | Conditions | High / Low | Precip | Wind | UV |
|---|---|---|---|---|---|
| Mon, Aug 24 | ☁️ Overcast | 80° / 54° | 6% | 6 mph | 7 |
| Tue, Aug 25 | ☁️ Overcast | 85° / 59° | 1% | 8 mph | 7 |
| Wed, Aug 26 | ⛈️ Thunderstorm | 88° / 65° | 26% · 0,5 in | 16 mph | 7 |
| Thu, Aug 27 | ☀️ Clear sky | 85° / 64° | 26% | 9 mph | 7 |
| Fri, Aug 28 | ☁️ Overcast | 85° / 63° | 1% | 8 mph | 7 |
| Sat, Aug 29 | ☁️ Overcast | 82° / 63° | 3% | 10 mph | 5 |
| Sun, Aug 30 | 🌦️ Light drizzle | 95° / 70° | 6% · 0,0 in | 17 mph | 7 |
| Mon, Aug 31 | 🌦️ Light showers | 95° / 69° | 12% · 0,5 in | 14 mph | 6 |
| Tue, Sep 1 | 🌤️ Mainly clear | 100° / 78° | 17% | 14 mph | 7 |
| Wed, Sep 2 | ⛅ Partly cloudy | 103° / 80° | 14% | 14 mph | 7 |
| Thu, Sep 3 | ⛈️ Violent showers | 101° / 69° | 16% · 1,5 in | 14 mph | 7 |
| Fri, Sep 4 | 🌦️ Light drizzle | 80° / 69° | 13% · 0,1 in | 9 mph | 2 |
| Sat, Sep 5 | 🌦️ Drizzle | 89° / 68° | 16% · 0,1 in | 8 mph | 6 |
| Sun, Sep 6 | 🌦️ Light showers | 92° / 70° | 22% · 0,3 in | 11 mph | 7 |
The two-week trend
Warming. The second half of the window averages 37°F warmer than the days immediately ahead.
The window averages 89°F against a August normal of 83°F - 38°F above.
Rainfall over the next 7 days is close to normal for August (0,5 in against a typical 0,4 in).
What this means for Illinois
Today is slightly cooler than average for August. The forecast high of 80°F is 2.7°F below the 83°F typical for this month.
Rain is very unlikely today - plans do not need a backup.
No weather-related travel disruption is expected today. Roads and airports should run normally.
Northern Hemisphere, so peak summer falls in June to August.
The gap between the warmest and coldest month averages 83°F.
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.
See the Illinois forecast by time range
Illinois weather - more answers
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 69°F (20°C) with clear. Humidity is 71% 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 8:50 PM.
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 August 24, 2026 at 8:50 PM local time. Live blocks refresh every 15 minutes; climate averages monthly.
