Illinois Klima and Average Vejr
Klima of Illinois: average temperatures, rainfall and seasons month by month.
Klima in Illinois month by month
Average high, average low and total rainfall, based on three years of reanalysis data.
| Måned | Avg high | Avg low | Regnfall | Rating |
|---|---|---|---|---|
| januar | 1° | -7° | 62 mm | ★★☆☆☆ |
| februar | 8° | -3° | 20 mm | ★★★☆☆ |
| marts | 15° | 4° | 90 mm | ★★★☆☆ |
| april | 19° | 9° | 135 mm | ★★★☆☆ |
| maj | 24° | 13° | 100 mm | ★★★★☆ |
| juni | 28° | 19° | 117 mm | ★★★★☆ |
| juli | 29° | 21° | 129 mm | ★★★★☆ |
| august | 29° | 19° | 75 mm | ★★★★☆ |
| september | 28° | 17° | 33 mm | ★★★★★ |
| oktober | 20° | 10° | 37 mm | ★★★★☆ |
| november | 12° | 4° | 79 mm | ★★★☆☆ |
| december | 6° | -2° | 62 mm | ★★☆☆☆ |
Klima type: Kontinental. Kilde: Open-Meteo archive (ERA5).
Recent extremes in Illinois
Højest and lowest readings observed in the last 3 years of reanalysis data - not all-time records.
How Illinois compares med nearby places
Annual averages, and the difference against Illinois.
| Place | Distance | Avg temp | vs here | Annual rain |
|---|---|---|---|---|
| Gateway Arch National Park | 137 km | 15°C | +1°C warmer | 1156 mm |
| St. Louis | 137 km | 15°C | +1°C warmer | 1156 mm |
| Missouri | 255 km | 15°C | +1°C warmer | 1006 mm |
| Indianapolis | 298 km | 13°C | 1°C cooler | 1135 mm |
| Indiana | 298 km | 13°C | 1°C cooler | 1135 mm |
Klima by city in Illinois
1 cities mapped in this atlas
Klima by state park in Illinois
1 state and provincial parks mapped in this atlas
Klima by county in Illinois
1 counties mapped in this atlas
Klima by lake in Illinois
1 lakes mapped in this atlas
Bedste rejsetid Illinois
Go in august, september and oktober. These months score highest on comfortable temperatures, low rainfall and useful daylight.
Hardest months: januar, februar and december - expect the least comfortable mix of heat, cold or rain.
What this means for Illinois
Today is warmer than average for oktober. The forecast high of 25°C is 5.1°C above the 20°C typical for this month.
Regn 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 juni og august.
The gap between the warmest and coldest month averages 29°C.
What og pack, what og skip
- sønglasses, a brimmed hat and SPF 30+
- Layers - the daily swing is 19°C, so mornings feel nothing like afternoons
- If your dates are flexible, avoid januar, februar and december - historically the least comfortable months here.
Resumé
Illinois is a state in USA. Illinois is a US state med hovedstad Springfield. Der bor omkring 12.6 million. Hovedstaden er Springfield.
Lige nu er det 14°C (57°F) in Illinois med mest klart. Det føles som 13°C. I dag ligger temperaturen mellem 7°C og 25°C. Sandsynligheden for nedbør er 0%. Sightseeing conditions score 9.6/10 - fremragende — tag af sted nu.
Det bedste tidspunkt at besøge Illinois is august, september and oktober. Klimaet er continental. januar, februar and december tend og be the least comfortable months. juli is the warmest month med average highs near 29°C, while januar is the coldest med lows near -7°C.
The closest major airport is O'Hare International Airport (ORD), about 284 km away. Nearby highlights include Starved Rock State Park, Lake Michigan, Gateway Arch National Park and Indiana Dunes National Park.
Kort sagt. Today is warmer than average for oktober. The forecast high of 25°C is 5.1°C above the 20°C typical for this month. The best window og be outside is roughly 11 AM og 2 PM, when temperature, rain chance and wind line up best. hiking is the strongest bet in Illinois today at 9.8/10. 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.
Quick facts about Illinois
| Type | State |
|---|---|
| Land | USA |
| Kontinent | Nordamerika |
| Koordinater | 39°46′54.1″N 89°39′0.4″W (39.7817, -89.6501) |
| Capital | Springfield |
| Befolkning | 12.600.000 |
| Area | 149.995 km² |
| Abbreviation | IL |
| Tidszone | America/Chicago |
| Lokal tid | 1:45 AM (UTC-05:00) |
| Best months | august, september and oktober |
| Klima | Kontinental |
Vejr map for Illinois
Animated model layers. Pick a layer og load it.
Animated layers by Vindy. For pin-level detail and nearby places, see the interactive map below.
Explore Illinois
Every topic we hold for this place, and the same topic for the places around it.
Klima for related places
Frequently asked questions
Where is Illinois?
Illinois is a state in USA. Its coordinates are 39.7817, -89.6501. It lies in Nordamerika.
What is the weather like in Illinois lige nu?
It is currently 14°C (57°F) med mest klart. Luftfugtighed is 71% and wind is 7 km/h.
When is the best time og visit Illinois?
august, september and oktober offer the most comfortable conditions in Illinois, which has a continental climate. januar, februar 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 1:45 AM.
How many people live in Illinois?
Illinois has a population of approximately 12.6 million.
What is the nearest airport og Illinois?
The closest airports are O'Hare International Airport (ORD), 284 km away and Nashville International Airport (BNA), 483 km away.
What are the top things og 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. |
|---|---|
| Prognose and observations | Open-Meteo (ECMWF and national models). |
| Luftkvalitet and pollen | Copernicus CAMS via Open-Meteo. US AQI scale. |
| Klima averages | ERA5 reanalysis via the Open-Meteo archive, aggregated over 3 years. |
| Official alerts | US National Vejr 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 oktober 26, 2026 at 1:45 AM local time. Live blocks refresh every 15 minutes; climate averages monthly.
