Illinois Väder Prognos
Illinois weather: 24°C, mulet. Varje timme forecast, 14-day outlook, UV, air quality and the best time och visit.
Illinois weather in augusti
One of the best months och visit Illinois.
augusti runs 10°C warmer than the annual average in Illinois.
Compare med september.
Väder map for Illinois
Animated model layers. Pick a layer och load it.
Animated layers by Vindy. For pin-level detail and nearby places, see the interactive map below.
Klimat in Illinois month by month
Average high, average low and total rainfall, based on three years of reanalysis data.
| Månad | Avg high | Avg low | Regnfall | Rating |
|---|---|---|---|---|
| januari | 1° | -7° | 62 mm | ★★☆☆☆ |
| februari | 8° | -3° | 20 mm | ★★★☆☆ |
| mars | 15° | 4° | 90 mm | ★★★☆☆ |
| april | 19° | 9° | 135 mm | ★★★☆☆ |
| maj | 24° | 13° | 100 mm | ★★★★☆ |
| juni | 28° | 19° | 117 mm | ★★★★☆ |
| juli | 29° | 21° | 129 mm | ★★★★☆ |
| augusti | 29° | 19° | 75 mm | ★★★★☆ |
| september | 28° | 17° | 33 mm | ★★★★★ |
| oktober | 20° | 10° | 37 mm | ★★★★☆ |
| november | 12° | 4° | 79 mm | ★★★☆☆ |
| december | 6° | -2° | 62 mm | ★★☆☆☆ |
Klimat type: Kontinental. Källa: Open-Meteo archive (ERA5).
Bästa tiden att besöka Illinois
Go in augusti, september and oktober. These months score highest on comfortable temperatures, low rainfall and useful daylight.
Hardest months: januari, februari and december - expect the least comfortable mix of heat, cold or rain.
What och pack, what och skip
- Lightweight, light-coloured clothing and a refillable water bottle
- sönglasses, a brimmed hat and SPF 30+
- Layers - the daily swing is 26°C, so mornings feel nothing like afternoons
- A packable rain shell - 2 of the next 7 days carry a real chance of rain
- Avoid exposed ridgelines, small boats and rooftop viewpoints while gusts stay above 51 km/h.
- If your dates are flexible, avoid januari, februari and december - historically the least comfortable months here.
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 |
Se prognosen för Illinois per tidsintervall
Illinois weather - more answers
Explore Illinois
Every topic we hold for this place, and the same topic for the places around it.
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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 just nu?
It is currently 24°C (75°F) med mulet. Luftfuktighet is 52% and wind is 10 km/h.
When is the best time och visit Illinois?
augusti, september and oktober offer the most comfortable conditions in Illinois, which has a continental climate. januari, februari 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 9:10 AM.
How many people live in Illinois?
Illinois has a population of approximately 12.6 million.
What is the nearest airport och 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 och 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. |
|---|---|
| Prognos and observations | Open-Meteo (ECMWF and national models). |
| Luftkvalitet and pollen | Copernicus CAMS via Open-Meteo. US AQI scale. |
| Klimat averages | ERA5 reanalysis via the Open-Meteo archive, aggregated over 3 years. |
| Official alerts | US National Väder 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 1, 2026 at 9:10 AM local time. Live blocks refresh every 15 minutes; climate averages monthly.
