Champaign weather in September

In September, Champaign sees average daytime highs of 78°F and overnight lows near 57°F, with 3.0 in of rain across 7.3 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 8th-wettest month of the year here.

Highs ease over the month, from about 82°F in the first days to 73°F by the end. The sky is clear or mostly clear about 47% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Champaign's 1st-clearest and 9th-windiest month. For the whole year in context, see Champaign's year-round climate.

Daytime high
78°
4th warmest
Overnight low
57°
9th coldest
Rainfall
3.0 in
7.3 wet days
Daylight
12 h 18 min
5:39 AM – 5:55 PM
Cloud cover
46%
1st clearest
Wind
7 mph
9th windiest
Solar energy
4.69 kWh/m²
Travel score
7.3
out of 10

Champaign is city in Champaign County, Illinois, United States.

Density
1,462/km²
people per km²
Founded
1855

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 82°F in the first days to 73°F by the end.

A typical September day in Champaign reaches about 78°F in the afternoon and slips back to 57°F overnight — a 21°F spread between the day's warmth and the night's chill. On most days the high lands between 67°F and 88°F. Set against its neighbours, September runs about 5°F cooler than August and about 13°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18263
28262
38262
48262
58161
68161
78160
88060
98060
108059
117959
127958
137958
147858
157857
167857
177756
187756
197756
207655
217655
227554
237554
247554
257453
267453
277452
287352
297352
307351

How September really feels in Champaign

Once humidity and wind are folded in, September averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Champaign weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 8th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan35° / 21°2.78.64.49.50.0
Feb40° / 24°2.37.43.810.40.2
Mar51° / 33°3.310.31.611.72.5
Apr64° / 44°4.511.80.3135.2
May73° / 54°4.713.2014.26.2
Jun81° / 64°4.111.4014.86.0
Jul84° / 67°3.610.4014.65.6
Aug83° / 65°2.98.7013.66.2
Sep78° / 57°3.07.3012.37.3
Oct65° / 46°3.38.50.110.96.1
Nov51° / 35°3.38.70.89.82.7
Dec40° / 26°2.58.93.19.20.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 47% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 14% of September, with mostly cloudy or overcast conditions the remaining 39%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16238
26238
36238
46337
56436
66436
76436
86436
96436
106337
116337
126238
136139
146139
156040
166040
175941
185941
195941
205941
215842
225941
235941
245941
255941
265941
275941
286040
296040
306040

Chance of precipitation in September

Any precipitation

Champaign gets around 3.0 in of rain over 7.3 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 25% and peaks near 27% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
127
226
326
426
526
625
725
825
925
1025
1125
1226
1326
1426
1526
1626
1726
1826
1926
2026
2126
2225
2325
2425
2525
2625
2725
2824
2924
3024

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the dry band about 47% of days. Sticky, muggy-or-worse air turns up on roughly 16% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
12020242511
22221232410
3232223239
4252223228
5272322217
6292322206
7312322195
8332321184
9352321184
10362321173
11382320163
12402220152
13422220152
14432120141
15452119131
16472019131
17491919121
18511918111
19541817110
20571716100
21571716100
2260161590
2361161490
2464151380
2565151280
2667141270
2768141170
2869131170
2971131060
3072121060

Wind in September

Winds average 7 mph in September.

Across September, daily wind ranges from about 7 mph on the calmest days to 8 mph at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147light breeze
157light breeze
168light breeze
178light breeze
188light breeze
198light breeze
208light breeze
218light breeze
228light breeze
238light breeze
248light breeze
258light breeze
268light breeze
278light breeze
288light breeze
298light breeze
308light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 54 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over September. Sunrise moves from 5:25 AM to 5:53 AM, and sunset from 6:21 PM to 5:31 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:256:21
212.95:266:19
312.85:276:17
412.85:286:16
512.85:296:14
612.75:306:12
712.75:316:11
812.65:326:09
912.65:336:07
1012.55:346:05
1112.55:356:04
1212.45:366:02
1312.45:376:00
1412.45:385:59
1512.35:395:57
1612.35:395:55
1712.25:405:53
1812.25:415:52
1912.15:425:50
2012.15:435:48
2112.05:445:46
2212.05:455:45
2311.95:465:43
2411.95:475:41
2511.95:485:40
2611.85:495:38
2711.85:505:36
2811.75:515:34
2911.75:525:33
3011.65:535:31

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.69 kWh/m².

For context, solar energy here swings from a low near 1.77 kWh/m² to a high of 6.41 kWh/m² in June across the year — September's 4.69 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.2Bright
25.2Bright
35.2Bright
45.1Bright
55.1Bright
65.0Bright
75.0Bright
85.0Bright
94.9Bright
104.9Bright
114.8Bright
124.8Bright
134.8Bright
144.7Bright
154.7Bright
164.6Bright
174.6Bright
184.6Bright
194.5Bright
204.5Bright
214.4Bright
224.4Bright
234.4Bright
244.3Bright
254.3Bright
264.3Bright
274.2Bright
284.2Bright
294.1Bright
304.1Bright
Planning a trip in September

Is September a good time to visit Champaign?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

7.3
Sightseeing
1st-best month of the year
6.6
Beach & pool
3rd-best month of the year

September is one of the better times to visit Champaign for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Champaign in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Champaign sees daytime highs around 78°F and nights near 57°F. Worth packing: light clothes and sun protection. About 7 days see rain.

light clothessun protection

UV index in Champaign in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Champaign peaks around June 23 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateJun 23UV 9Jan 1UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Champaign in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Champaign is worst in July — around 16 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (October, 8 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateModerateGoodJul 1616 µg/m³Oct 218 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb13Moderate
Mar13Moderate
Apr11Good
May14Moderate
Jun15Moderate
Jul16Moderate
Aug14Moderate
Sep11Good
Oct8Good
Nov8Good
Dec9Good
Location & terrain

Where is Champaign?

Champaign sits at 40.1°N, 88.2°W, 738 ft above sea level, in United States. The nearest listed city is Urbana, 1.9 mi away.

Topography around Champaign

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Champaign.

Within 2 miles, the terrain around Champaign has only modest variations in elevation — a maximum elevation change of 115 ft around an average of 751 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 200 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 495 ft.

The land around Champaign is covered by artificial surfaces (47%) and trees (37%) within 2 miles, cropland (79%) within 10 miles, and cropland (86%) within 50 miles.

2 miles
115 ft
10 miles
200 ft
50 miles
495 ft
treesgrasslandcroplandartificial surfacesbare terrain
September weather nearby: Urbana 1.9 mi · Danville 32 mi · Decatur 42 mi · Charleston 43 mi · Mattoon 44 mi · Bloomington 47 mi · Normal 48 mi · Terre Haute 63 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Champaign (40.1164°, -88.2434°, elevation 738 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).