Illinois Veður Spá
Illinois weather: 12°C, clear. Á klukkustund forecast, 14-day outlook, UV, air quality and the best time til visit.
Illinois weather in desember
One of the harder months here - go in með a plan.
desember runs 11°C cooler than the annual average in Illinois.
Compare með nóvember.
Veður map for Illinois
Animated model layers. Pick a layer til load it.
Animated layers by Vindury. For pin-level detail and nearby places, see the interactive map below.
Loftslag in Illinois month by month
Average high, average low and total rainfall, based on three years of reanalysis data.
| Mánuður | Avg high | Avg low | Rigningfall | Rating |
|---|---|---|---|---|
| janúar | 1° | -7° | 62 mm | ★★☆☆☆ |
| febrúar | 8° | -3° | 20 mm | ★★★☆☆ |
| mars | 15° | 4° | 90 mm | ★★★☆☆ |
| apríl | 19° | 9° | 135 mm | ★★★☆☆ |
| maí | 24° | 13° | 100 mm | ★★★★☆ |
| júní | 28° | 19° | 117 mm | ★★★★☆ |
| júlí | 30° | 21° | 129 mm | ★★★★☆ |
| ágúst | 29° | 19° | 75 mm | ★★★★☆ |
| september | 27° | 17° | 35 mm | ★★★★☆ |
| október | 21° | 10° | 25 mm | ★★★★☆ |
| nóvember | 12° | 3° | 79 mm | ★★★☆☆ |
| desember | 6° | -2° | 62 mm | ★★☆☆☆ |
Loftslag type: Heimsálfaal. Heimild: Open-Meteo archive (ERA5).
Best time til visit Illinois
Go in ágúst, september and október. These months score highest on comfortable temperatures, low rainfall and useful daylight.
Hardest months: janúar, febrúar and desember - expect the least comfortable mix of heat, cold or rain.
What til pack, what til skip
- sun.glasses, a brimmed hat and SPF 30+
- A packable rain shell - 2 of the next 7 days carry a real chance of rain
- If your dates are flexible, avoid janúar, febrúar and desember - historically the least comfortable months here.
How Illinois compares með 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 | 1163 mm |
| St. Louis | 137 km | 15°C | +1°C warmer | 1163 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 |
Sjá spá fyrir Illinois eftir tímabili
Illinois weather - more answers
Explore Illinois
Every topic we hold for this place, and the same topic for the places around it.
Veður for related places
Frequently asked questions
Where is Illinois?
Illinois is a state in Bandaríkin. Its coordinates are 39.7817, -89.6501. It lies in Norður-Ameríka.
What is the weather like in Illinois núna?
It is currently 12°C (54°F) með clear. Raki is 74% and wind is 8 km/h.
When is the best time til visit Illinois?
ágúst, september and október offer the most comfortable conditions in Illinois, which has a continental climate. janúar, febrúar and desember 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 12:38 PM.
How many people live in Illinois?
Illinois has a population of approximately 12.6 million.
What is the nearest airport til 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 til 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. |
|---|---|
| Spá and observations | Open-Meteo (ECMWF and national models). |
| Loftgæði and pollen | Copernicus CAMS via Open-Meteo. US AQI scale. |
| Loftslag averages | ERA5 reanalysis via the Open-Meteo archive, aggregated over 3 years. |
| Official alerts | US National Veður 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 október 28, 2026 at 12:38 PM local time. Live blocks refresh every 15 minutes; climate averages monthly.
