Illinois Ilmasto and Average Sää
Ilmasto of Illinois: average temperatures, rainfall and seasons month by month.
Ilmasto in Illinois month by month
Average high, average low and total rainfall, based on three years of reanalysis data.
| Kuukausi | Avg high | Avg low | Sadefall | Rating |
|---|---|---|---|---|
| tammikuu | 1° | -7° | 62 mm | ★★☆☆☆ |
| helmikuu | 8° | -3° | 20 mm | ★★★☆☆ |
| maaliskuu | 15° | 4° | 90 mm | ★★★☆☆ |
| huhtikuu | 19° | 9° | 135 mm | ★★★☆☆ |
| tou | 24° | 13° | 100 mm | ★★★★☆ |
| kesäkuu | 28° | 19° | 117 mm | ★★★★☆ |
| heinäkuu | 29° | 21° | 129 mm | ★★★★☆ |
| elokuu | 29° | 19° | 75 mm | ★★★★☆ |
| syyskuu | 28° | 17° | 33 mm | ★★★★★ |
| lokakuu | 20° | 10° | 37 mm | ★★★★☆ |
| marraskuu | 12° | 4° | 79 mm | ★★★☆☆ |
| joulukuu | 6° | -2° | 62 mm | ★★☆☆☆ |
Ilmasto type: Maanosaal. Lähde: Open-Meteo archive (ERA5).
Recent extremes in Illinois
Korkeaest and lowest readings observed in the last 3 years of reanalysis data - not all-time records.
How Illinois compares ja 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 |
Ilmasto by city in Illinois
1 cities mapped in this atlas
Ilmasto by state park in Illinois
1 state and provincial parks mapped in this atlas
Ilmasto by county in Illinois
1 counties mapped in this atlas
Ilmasto by lake in Illinois
1 lakes mapped in this atlas
Paras aika vierailla Illinois
Go in elokuu, syyskuu and lokakuu. These months score highest on comfortable temperatures, low rainfall and useful daylight.
Hardest months: tammikuu, helmikuu and joulukuu - expect the least comfortable mix of heat, cold or rain.
What this means for Illinois
Today is slightly warmer than average for lokakuu. The forecast high of 24°C is 3.6°C above the 20°C typical for this month.
Sade 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 kesäkuu ja elokuu.
The gap between the warmest and coldest month averages 29°C.
What ja pack, what ja skip
- suglasses, 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 tammikuu, helmikuu and joulukuu - historically the least comfortable months here.
Yhteenveto
Illinois is a state in Yhdysvallat. Illinois is a US state jonka pääkaupunki on Springfield. Väkiluku on noin 12.6 million. Pääkaupunki on Springfield.
Tällä hetkellä lämpötila on 18°C (64°F) in Illinois ja selkeä. Tuntuu kuin 15°C. Tänään lämpötila vaihtelee 7°C ja 24°C. laeen todennäköisyys on 0%. Sightseeing conditions score 9.7/10 - erinomainen — lähde nyt.
Paras aika matkustaa kohteeseen Illinois is elokuu, syyskuu and lokakuu. Ilmasto on continental. tammikuu, helmikuu and joulukuu tend ja be the least comfortable months. heinäkuu is the warmest month ja average highs near 29°C, while tammikuu is the coldest ja 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.
Yksinkertaisesti sanottuna. Today is slightly warmer than average for lokakuu. The forecast high of 24°C is 3.6°C above the 20°C typical for this month. The best window ja be outside is roughly 11 AM ja 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
| Tyyppi | State |
|---|---|
| Maa | Yhdysvallat |
| Maanosa | Pohjois-Amerikka |
| Koordinaatit | 39°46′54.1″N 89°39′0.4″W (39.7817, -89.6501) |
| Capital | Springfield |
| Väkiluku | 12.600.000 |
| Area | 149.995 km² |
| Abbreviation | IL |
| Aikavyöhyke | America/Chicago |
| Paikallinen aika | 4:16 PM (UTC-05:00) |
| Best months | elokuu, syyskuu and lokakuu |
| Ilmasto | Maanosaal |
Sää map for Illinois
Animated model layers. Pick a layer ja load it.
Animated layers by Tuuliy. 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.
Ilmasto for related places
Frequently asked questions
Where is Illinois?
Illinois is a state in Yhdysvallat. Its coordinates are 39.7817, -89.6501. It lies in Pohjois-Amerikka.
What is the weather like in Illinois nyt?
It is currently 18°C (64°F) ja selkeä. Kosteus is 39% and wind is 8 km/h.
When is the best time ja visit Illinois?
elokuu, syyskuu and lokakuu offer the most comfortable conditions in Illinois, which has a continental climate. tammikuu, helmikuu and joulukuu 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 4:16 PM.
How many people live in Illinois?
Illinois has a population of approximately 12.6 million.
What is the nearest airport ja 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 ja 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. |
|---|---|
| Ennuste and observations | Open-Meteo (ECMWF and national models). |
| Ilmanlaatu and pollen | Copernicus CAMS via Open-Meteo. US AQI scale. |
| Ilmasto averages | ERA5 reanalysis via the Open-Meteo archive, aggregated over 3 years. |
| Official alerts | US National Sää 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 lokakuu 25, 2026 at 4:16 PM local time. Live blocks refresh every 15 minutes; climate averages monthly.
