Best Time to Visit Illinois
Best time to visit Illinois: May, July, August, September and October. Month-by-month temperature, rainfall and crowd guidance.
Best time to visit Illinois
Go in May, July, 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.
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° | 3,8 in | ★★★★☆ |
| August | 83° | 67° | 2,4 in | ★★★★☆ |
| September | 80° | 61° | 1,7 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).
How Illinois compares with nearby places
Annual averages, and the difference against Illinois.
| Place | Distance | Avg temp | vs here | Annual rain |
|---|---|---|---|---|
| Gateway Arch National Park | 85 mi | 58°F | +34°F warmer | 45 in |
| St. Louis | 85 mi | 58°F | +34°F warmer | 45 in |
| Indianapolis | 185 mi | 55°F | 33°F cooler | 42 in |
| Indiana | 185 mi | 55°F | 33°F cooler | 42 in |
| Indiana Dunes National Park | 188 mi | 52°F | 35°F cooler | 42 in |
Best time to visit each city in Illinois
1 cities mapped in this atlas
Best time to visit each state park in Illinois
1 state and provincial parks mapped in this atlas
Best time to visit each county in Illinois
1 counties mapped in this atlas
Best time to visit each lake in Illinois
1 lakes mapped in this atlas
What to pack, what to skip
- Lightweight, light-coloured clothing and a refillable water bottle
- Sunglasses, a brimmed hat and SPF 30+
- A packable rain shell - 3 of the next 7 days carry a real chance of rain
- If your dates are flexible, avoid January, February and December - historically the least comfortable months here.
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 72°F (22°C) in Illinois with clear sky. It feels like 73°F. Today runs from 68°F to 89°F. Chance of precipitation is 44%. Sightseeing conditions score 8.5/10 - excellent - go now.
The best time to visit Illinois is May, July, 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 August. The forecast high of 89°F is 5.9°F above the 83°F typical for this month. The best window to be outside is roughly 8 AM to 11 AM, when temperature, rain chance and wind line up best. stargazing is the strongest bet in Illinois today at 8.6/10. 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 7:46 AM, Aug 5 local time.
Weekend outlook
🌦️ 87° / 67°
Light showers · 43% rain · wind 13 mph
🌦️ 90° / 73°
Light drizzle · 22% rain · wind 18 mph
Things to do in Illinois
Attractions, parks and landmarks in and around Illinois.
Quick facts about Illinois
| Type | State |
|---|---|
| Country | United States |
| Continent | North America |
| Coordinates | 39°46′54.1″N 89°39′0.4″W (39.7817, -89.6501) |
| Capital | Springfield |
| Population | 12.600.000 |
| Area | 57.913 sq mi |
| Abbreviation | IL |
| Time zone | America/Chicago |
| Local time | 7:46 AM (UTC-05:00) |
| Best months | May, July, August, September and October |
| Climate | Continental |
Explore Illinois
Every topic we hold for this place, and the same topic for the places around it.
Best Time to Visit 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 72°F (22°C) with clear sky. Humidity is 73% and wind is 7 mph.
When is the best time to visit Illinois?
May, July, 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 7:46 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 August 5, 2026 at 7:46 AM local time. Live blocks refresh every 15 minutes; climate averages monthly.
