Onalaska weather in September

In September, Onalaska sees average daytime highs of 71°F and overnight lows near 53°F, with 3.2 in of rain across 9.4 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 76°F in the first days to 66°F by the end. The sky is clear or mostly clear about 39% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 06 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Onalaska's 1st-clearest and 9th-windiest month. For the whole year in context, see Onalaska's year-round climate.

Daytime high
71°
4th warmest
Overnight low
53°
9th coldest
Rainfall
3.2 in
9.4 wet days
Daylight
12 h 18 min
5:50 AM – 6:08 PM
Cloud cover
52%
1st clearest
Wind
7 mph
9th windiest
Solar energy
4.2 kWh/m²
Travel score
6.8
out of 10

Onalaska is fourth-class city in La Crosse County, Wisconsin, United States.

Density
659/km²
people per km²
Founded
1851

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 76°F in the first days to 66°F by the end.

A typical September day in Onalaska reaches about 71°F in the afternoon and slips back to 53°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 60°F and 82°F. Set against its neighbours, September runs about 7°F cooler than August and about 14°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
17758
27658
37658
47657
57657
67557
77556
87456
97456
107455
117355
127355
137354
147254
157253
167153
177153
187152
197052
207051
216951
226951
236850
246850
256749
266749
276748
286648
296647
306547

How September really feels in Onalaska

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.

Onalaska weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan26° / 10°1.376.49.10.0
Feb30° / 14°1.26.15.110.20.0
Mar43° / 26°2.38.94.111.60.7
Apr56° / 38°3.611.5213.23.7
May68° / 49°4.212.80.114.55.8
Jun77° / 60°4.812.3015.26.3
Jul81° / 64°3.910.6014.96.5
Aug78° / 61°3.69.3013.86.9
Sep71° / 53°3.29.4012.36.8
Oct58° / 41°2.88.80.510.84.4
Nov43° / 29°2.06.839.50.7
Dec30° / 17°1.57.168.80.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 39% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 45%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16040
26040
36040
46040
56040
66040
75941
85941
95842
105743
115644
125644
135545
145446
155446
165446
175347
185248
195248
205248
215248
225248
235149
245149
255248
265248
275248
285248
295248
305248

Chance of precipitation in September

Any precipitation

Onalaska gets around 3.2 in of rain over 9.4 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 31% and peaks near 33% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
128
228
328
429
529
629
729
830
930
1031
1131
1231
1332
1432
1532
1632
1733
1833
1933
2033
2133
2233
2333
2432
2532
2632
2732
2832
2932
3031

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 60% of days. Sticky, muggy-or-worse air turns up on roughly 8% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1352322163
2372322153
3392321143
4412321133
5432320122
6452220112
7462219102
8482219102
950221991
1051211891
1153211781
1253211781
1356211670
1458201570
1558201570
1660201460
1762191360
1862191360
1965181250
2066181150
2168171050
2270161040
237215940
247514830
257613830
267713730
277912720
288111620
298210620
30849520

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.

0246810151015202530
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207light breeze
217light 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 13 h 06 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 90 minutes over September. Sunrise moves from 5:33 AM to 6:07 AM, and sunset from 6:36 PM to 5:41 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.15:336:36
213.05:346:35
313.05:356:33
412.95:366:31
512.95:376:29
612.85:396:27
712.85:406:25
812.75:416:23
912.75:426:22
1012.65:436:20
1112.65:446:18
1212.55:466:16
1312.55:476:14
1412.45:486:12
1512.35:496:10
1612.35:506:08
1712.25:526:06
1812.25:536:04
1912.15:546:02
2012.15:556:00
2112.05:565:59
2212.05:575:57
2311.95:595:55
2411.96:005:53
2511.86:015:51
2611.86:025:49
2711.76:035:47
2811.76:055:45
2911.66:065:43
3011.66:075:41

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.2 kWh/m².

For context, solar energy here swings from a low near 1.48 kWh/m² to a high of 6.22 kWh/m² in July across the year — September's 4.2 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.9Bright
24.8Bright
34.8Bright
44.8Bright
54.7Bright
64.7Bright
74.6Bright
84.6Bright
94.5Bright
104.4Bright
114.4Bright
124.3Bright
134.3Bright
144.2Bright
154.2Bright
164.1Bright
174.1Bright
184.0Bright
194.0Moderate
203.9Moderate
213.9Moderate
223.9Moderate
233.8Moderate
243.8Moderate
253.7Moderate
263.7Moderate
273.7Moderate
283.6Moderate
293.6Moderate
303.5Moderate
Planning a trip in September

Is September a good time to visit Onalaska?

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

6.8
Sightseeing
2nd-best month of the year
4.6
Beach & pool
4th-best month of the year

September is a reasonable time to visit Onalaska for sightseeing.

What to pack for Onalaska in September

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

In September, Onalaska sees daytime highs around 71°F and nights near 53°F. Worth packing: rain gear. About 9 days see rain.

rain gear

UV index in Onalaska 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 Onalaska peaks around June 14 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 11 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 14UV 9Jan 11UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar3Moderate
Apr5High
May8Very high
Jun9Very high
Jul7High
Aug7Very high
Sep6High
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Onalaska?

Onalaska sits at 43.9°N, 91.2°W, 709 ft above sea level, in United States. The nearest listed city is North La Crosse, 2.5 mi away.

Topography around Onalaska

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

Within 2 miles, the terrain around Onalaska has only modest variations in elevation — a maximum elevation change of 581 ft around an average of 696 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 748 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 860 ft.

The land around Onalaska is covered by artificial surfaces (34%), trees (28%) and grassland (21%) within 2 miles, trees (53%) within 10 miles, and trees (54%) and cropland (33%) within 50 miles.

2 miles
581 ft
10 miles
748 ft
50 miles
860 ft
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: North La Crosse 2.5 mi · La Crosse 5.6 mi · Winona 23 mi · Rochester 62 mi · Eau Claire 65 mi · Marshfield 76 mi · Menomonie 76 mi · Wisconsin Rapids 78 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 Onalaska (43.8844°, -91.2351°, elevation 709 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. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).