Bloomington weather in September

In September, Bloomington sees average daytime highs of 78°F and overnight lows near 58°F, with 2.9 in of rain across 7.9 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 11th-wettest month of the year here.

Highs ease over the month, from about 82°F in the first days to 74°F by the end. The sky is clear or mostly clear about 43% 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 Bloomington's 1st-clearest and 9th-windiest month. For the whole year in context, see Bloomington's year-round climate.

Daytime high
78°
4th warmest
Overnight low
58°
9th coldest
Rainfall
2.9 in
7.9 wet days
Daylight
12 h 18 min
6:33 AM – 6:48 PM
Cloud cover
49%
1st clearest
Wind
6 mph
9th windiest
Solar energy
4.63 kWh/m²
Travel score
7.1
out of 10

Bloomington is county seat of Monroe County, Indiana, United States.

Density
1,385/km²
people per km²
Founded
1818

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 74°F by the end.

A typical September day in Bloomington reaches about 78°F in the afternoon and slips back to 58°F overnight — a 20°F spread between the day's warmth and the night's chill. On most days the high lands between 68°F and 88°F. Set against its neighbours, September runs about 6°F cooler than August and about 12°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18364
28363
38263
48263
58262
68262
78162
88161
98061
108060
118060
128060
137959
147959
157858
167858
177858
187757
197757
207756
217656
227656
237655
247555
257554
267454
277454
287453
297353
307353

How September really feels in Bloomington

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.

Bloomington weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan38° / 24°3.49.53.79.60.0
Feb42° / 26°2.98.43.410.50.4
Mar53° / 35°4.010.81.711.72.8
Apr64° / 45°5.012.40.2135.3
May73° / 56°5.113.4014.16.2
Jun82° / 65°4.411.9014.75.8
Jul85° / 68°3.511.5014.55.1
Aug84° / 66°3.19013.55.7
Sep78° / 58°2.97.9012.37.1
Oct66° / 47°3.38.30116.2
Nov52° / 37°3.68.90.79.92.9
Dec42° / 28°3.4103.29.30.3

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 43% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 40%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15941
25941
35941
45941
55941
65941
76040
86040
95941
105941
115941
126040
135941
145941
155941
165842
175842
185842
195941
206040
216040
226040
236139
246139
256139
266139
276139
286238
296238
306238

Chance of precipitation in September

Any precipitation

Bloomington gets around 2.9 in of rain over 7.9 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 27% and peaks near 28% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
127
227
327
427
526
626
726
825
925
1025
1125
1226
1326
1426
1527
1627
1727
1827
1928
2028
2128
2228
2328
2428
2528
2627
2727
2826
2926
3025

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 42% of days. Sticky, muggy-or-worse air turns up on roughly 20% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
11721222713
21822222612
32022222611
42123212510
5232321249
6242321238
7262421227
8282422206
9302421205
10312421195
11332421184
12352421174
13362321173
14382320163
15402319152
16422219152
17442218142
18462117141
19492116131
20512015131
21522015121
22541914121
23561913111
24591812101
25591812101
2662171191
2763161191
2863161191
2965151181
3067151080

Wind in September

Winds average 6 mph in September.

Across September, daily wind ranges from about 5 mph on the calmest days to 6 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

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 6:19 AM to 6:46 AM, and sunset from 7:13 PM to 6:25 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.96:197:13
212.96:207:11
312.86:217:10
412.86:227:08
512.76:237:06
612.76:247:05
712.66:247:03
812.66:257:01
912.66:267:00
1012.56:276:58
1112.56:286:56
1212.46:296:55
1312.46:306:53
1412.36:316:51
1512.36:326:50
1612.36:336:48
1712.26:346:46
1812.26:356:45
1912.16:366:43
2012.16:376:41
2112.06:386:40
2212.06:396:38
2311.96:396:36
2411.96:406:35
2511.96:416:33
2611.86:426:31
2711.86:436:30
2811.76:446:28
2911.76:456:26
3011.66:466:25

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.63 kWh/m².

For context, solar energy here swings from a low near 1.72 kWh/m² to a high of 6.26 kWh/m² in June across the year — September's 4.63 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.1Bright
25.1Bright
35.1Bright
45.0Bright
55.0Bright
65.0Bright
74.9Bright
84.9Bright
94.8Bright
104.8Bright
114.8Bright
124.8Bright
134.7Bright
144.7Bright
154.6Bright
164.6Bright
174.6Bright
184.5Bright
194.5Bright
204.5Bright
214.4Bright
224.4Bright
234.3Bright
244.3Bright
254.3Bright
264.2Bright
274.2Bright
284.2Bright
294.1Bright
304.1Bright
Planning a trip in September

Is September a good time to visit Bloomington?

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

7.1
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 Bloomington for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Bloomington in September

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

In September, Bloomington sees daytime highs around 78°F and nights near 58°F. Worth packing: light clothes and sun protection. About 8 days see rain.

light clothessun protection

UV index in Bloomington 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 Bloomington peaks around July 10 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 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 highHighModerateJul 10UV 9Dec 22UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May7Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov3Moderate
Dec2Low

Air quality in Bloomington 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 Bloomington is worst in July — around 17 µg/m³ PM2.5 (moderate), about 2.4× the cleanest month (October, 7 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1316 µg/m³Oct 237 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb11Good
Mar11Good
Apr11Good
May13Moderate
Jun15Moderate
Jul17Moderate
Aug13Moderate
Sep10Good
Oct7Good
Nov7Good
Dec8Good
Location & terrain

Where is Bloomington?

Bloomington sits at 39.2°N, 86.5°W, 771 ft above sea level, in United States. The nearest listed city is Columbus, 32 mi away.

Topography around Bloomington

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

Within 2 miles, the terrain around Bloomington has only modest variations in elevation — a maximum elevation change of 262 ft around an average of 807 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 554 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 732 ft.

The land around Bloomington is covered by trees (47%) and artificial surfaces (36%) within 2 miles, trees (71%) within 10 miles, and trees (49%) and cropland (37%) within 50 miles.

2 miles
262 ft
10 miles
554 ft
50 miles
732 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Columbus 32 mi · Franklin 34 mi · Seymour 37 mi · Plainfield 38 mi · Greenwood 39 mi · Avon 42 mi · Indianapolis 46 mi · Fairfield Heights 47 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 Bloomington (39.1653°, -86.5264°, elevation 771 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).