Illinois Climat and Average Météo
Climat of Illinois: average temperatures, rainfall and seasons month by month.
Climat in Illinois month by month
Average high, average low and total rainfall, based on three years of reanalysis data.
| Mois | Max moyenne | Min moyenne | Précipitations | Évaluation |
|---|---|---|---|---|
| janvier | 1° | -7° | 62 mm | ★★☆☆☆ |
| février | 8° | -3° | 20 mm | ★★★☆☆ |
| mars | 15° | 4° | 90 mm | ★★★☆☆ |
| avril | 19° | 9° | 135 mm | ★★★☆☆ |
| mai | 24° | 13° | 100 mm | ★★★★☆ |
| juin | 28° | 19° | 117 mm | ★★★★☆ |
| juillet | 29° | 21° | 129 mm | ★★★★☆ |
| août | 29° | 19° | 75 mm | ★★★★☆ |
| septembre | 28° | 17° | 33 mm | ★★★★★ |
| octobre | 20° | 10° | 37 mm | ★★★★☆ |
| novembre | 12° | 4° | 79 mm | ★★★☆☆ |
| décembre | 6° | -2° | 62 mm | ★★☆☆☆ |
Climat type: Continental. Source : Open-Meteo archive (ERA5).
Recent extremes in Illinois
Élevéest and lowest readings observed in the last 3 years of reanalysis data – not all-time records.
How Illinois compares avec 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 |
Climat by city in Illinois
1 cities mapped in this atlas
Climat by state park in Illinois
1 state and provincial parks mapped in this atlas
Climat by county in Illinois
1 counties mapped in this atlas
Climat by lake in Illinois
1 lakes mapped in this atlas
Meilleur moment pour visiter Illinois
Go in août, septembre and octobre. These months score highest on comfortable temperatures, low rainfall and useful daylight.
Hardest months: janvier, février and décembre – expect the least comfortable mix of heat, cold or rain.
What this means for Illinois
Today is slightly warmer than average for octobre. The forecast high of 24°C is 3.6°C above the 20°C typical for this month.
Pluie 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 juin à août.
The gap between the warmest and coldest month averages 29°C.
What à pack, what à skip
- dim.glasses, 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 janvier, février and décembre – historically the least comfortable months here.
Résumé
Illinois is a state in États-Unis. Illinois is a US state dont la capitale est Springfield. Sa population est d’environ 12.6 million. La capitale est Springfield.
Actuellement, il fait 18°C (64°F) in Illinois avec ciel dégagé. La température ressentie est de 15°C. Aujourd’hui, les températures vont de 7°C à 24°C. La probabilité de précipitations est de 0%. Les conditions pour les visites obtiennent 9.7/10 – excellent — partez maintenant.
La meilleure période pour visiter Illinois is août, septembre and octobre. Le climat est continental. janvier, février and décembre sont généralement les mois les moins confortables. juillet est le mois le plus chaud, avec des maximales moyennes proches de 29°C, tandis que janvier est le mois le plus froid, avec des minimales proches de -7°C.
L’aéroport principal le plus proche est O'Hare International Airport (ORD), about 284 km away. Parmi les sites à proximité, citons Starved Rock State Park, Lake Michigan, Gateway Arch National Park and Indiana Dunes National Park.
En termes simples. Today is slightly warmer than average for octobre. The forecast high of 24°C is 3.6°C above the 20°C typical for this month. The best window à be outside is roughly 11 AM à 2 PM, when temperature, rain chance and wind line up best. stargazing is the strongest bet in Illinois today at 10/10. 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 |
|---|---|
| Pays | États-Unis |
| Continent | Amérique du Nord |
| Coordonnées | 39°46′54.1″N 89°39′0.4″W (39.7817, -89.6501) |
| Capital | Springfield |
| Population | 12.600.000 |
| Area | 149.995 km² |
| Abbreviation | IL |
| Fuseau horaire | America/Chicago |
| Heure locale | 2:29 AM (UTC-05:00) |
| Meilleurs mois | août, septembre and octobre |
| Climat | Continental |
Météo map for Illinois
Animated model layers. Pick a layer à load it.
Animated layers by Venty. 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.
Climat for related places
Frequently asked questions
Where is Illinois?
Illinois is a state in États-Unis. Its coordinates are 39.7817, -89.6501. It lies in Amérique du Nord.
What is the weather like in Illinois maintenant?
It is currently 18°C (64°F) avec ciel dégagé. Humidité is 39% and wind is 8 km/h.
When is the best time à visit Illinois?
août, septembre and octobre offer the most comfortable conditions in Illinois, which has a continental climate. janvier, février and décembre are usually the hardest months for outdoor plans.
What time zone is Illinois in?
Illinois observes America/Chicago (UTC-05:00). The heure locale is 2:29 AM.
How many people live in Illinois?
Illinois has a population of approximately 12.6 million.
What is the nearest airport à 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 à 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. |
|---|---|
| Prévisions and observations | Open-Meteo (ECMWF and national models). |
| Qualité de l’air and pollen | Copernicus CAMS via Open-Meteo. US AQI scale. |
| Climat averages | ERA5 reanalysis via the Open-Meteo archive, aggregated over 3 years. |
| Official alerts | US National Météo 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 octobre 24, 2026 at 2:29 AM heure locale. Live blocks refresh every 15 minutes; climate averages monthly.
