Sioux Falls weather in September

In September, Sioux Falls sees average daytime highs of 73°F and overnight lows near 52°F, with 3.2 in of rain across 7.9 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 78°F in the first days to 68°F by the end. The sky is clear or mostly clear about 50% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 hours at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Sioux Falls's 1st-clearest and 8th-windiest month. For the whole year in context, see Sioux Falls's year-round climate.

Daytime high
73°
4th warmest
Overnight low
52°
9th coldest
Rainfall
3.2 in
7.9 wet days
Daylight
12 h 18 min
6:12 AM – 6:30 PM
Cloud cover
43%
1st clearest
Wind
10 mph
8th windiest
Solar energy
4.55 kWh/m²
Travel score
7.2
out of 10

Sioux Falls is city in and seat of Minnehaha County, and largest city in South Dakota, United States.

Density
872/km²
people per km²
Founded
1856

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 78°F in the first days to 68°F by the end.

A typical September day in Sioux Falls reaches about 73°F in the afternoon and slips back to 52°F overnight — a 21°F spread between the day's warmth and the night's chill. On most days the high lands between 61°F and 85°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)
17858
27858
37857
47857
57756
67756
77656
87655
97655
107554
117554
127453
137453
147453
157352
167352
177251
187251
197250
207150
217149
227149
237048
247048
256947
266947
276947
286846
296846
306745

How September really feels in Sioux Falls

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.

Sioux Falls 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°0.84.74.49.10.0
Feb31° / 13°0.94.84.410.20.0
Mar43° / 24°1.86.63.711.61.0
Apr57° / 36°3.610.32.213.24.0
May69° / 49°4.512.5014.55.9
Jun78° / 59°5.112.5015.26.4
Jul82° / 64°3.38.9014.96.5
Aug80° / 61°3.38.8013.87.0
Sep73° / 52°3.27.9012.37.2
Oct59° / 39°2.470.710.85.0
Nov43° / 25°1.65.53.19.50.9
Dec30° / 15°1.054.88.80.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 50% 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 34%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17030
27030
37030
47030
57030
67030
76931
86931
96832
106733
116634
126634
136535
146436
156436
166337
176337
186337
196337
206337
216337
226337
236436
246436
256436
266436
276337
286337
296337
306337

Chance of precipitation in September

Any precipitation

Sioux Falls gets around 3.2 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 30% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
125
225
326
426
527
627
727
828
928
1028
1129
1229
1330
1430
1530
1630
1730
1830
1929
2028
2128
2227
2326
2426
2525
2625
2725
2825
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 62% 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 (%)
1332124203
2352123192
3372122172
4402122161
5422121151
6442021141
7472020131
8491919120
9511919110
10531918100
1156181790
1257181780
1360171670
1461171570
1563161560
1664161460
1767151350
1868141350
1970141240
2072131140
2174121040
227612930
237711930
247911820
258110720
268110720
27849610
28859510
29859510
30869410

Wind in September

Winds average 10 mph in September.

Across September, daily wind ranges from about 9 mph on the calmest days to 10 mph at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (mph)Feels
19light breeze
29light breeze
39light breeze
49light breeze
59light breeze
69light breeze
79light breeze
810light breeze
910light breeze
1010light breeze
1110light breeze
1210light breeze
1310light breeze
1410light breeze
1510light breeze
1610light breeze
1710light breeze
1810light breeze
1910light breeze
2010light breeze
2110light breeze
2210light breeze
2310light breeze
2410light breeze
2510light breeze
2610light breeze
2710light breeze
2810light breeze
2910light breeze
3010light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 hours 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 84 minutes over September. Sunrise moves from 5:55 AM to 6:29 AM, and sunset from 6:58 PM to 6:04 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:556:58
213.05:566:56
312.95:576:54
412.95:596:53
512.96:006:51
612.86:016:49
712.76:026:47
812.76:036:45
912.66:046:43
1012.66:056:41
1112.56:076:40
1212.56:086:38
1312.46:096:36
1412.46:106:34
1512.36:116:32
1612.36:126:30
1712.26:146:28
1812.26:156:26
1912.16:166:24
2012.16:176:22
2112.06:186:21
2212.06:196:19
2311.96:216:17
2411.96:226:15
2511.86:236:13
2611.86:246:11
2711.76:256:09
2811.76:266:07
2911.66:286:05
3011.66:296:04

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.55 kWh/m².

For context, solar energy here swings from a low near 1.73 kWh/m² to a high of 6.67 kWh/m² in July across the year — September's 4.55 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.2Bright
45.1Bright
55.1Bright
65.0Bright
75.0Bright
84.9Bright
94.8Bright
104.8Bright
114.7Bright
124.7Bright
134.6Bright
144.5Bright
154.5Bright
164.4Bright
174.4Bright
184.3Bright
194.3Bright
204.3Bright
214.2Bright
224.2Bright
234.1Bright
244.1Bright
254.1Bright
264.0Bright
274.0Bright
284.0Moderate
293.9Moderate
303.9Moderate
Planning a trip in September

Hazard calendar for Sioux Falls

In seasonPeak

In September, Sioux Falls sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Sioux Falls's rainy season runs April–October, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Sioux Falls?

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

7.2
Sightseeing
1st-best month of the year
5.3
Beach & pool
4th-best month of the year

September is one of the better times to visit Sioux Falls for general sightseeing.

What to pack for Sioux Falls in September

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

In September, Sioux Falls sees daytime highs around 73°F and nights near 52°F. Worth packing: light clothes and sun protection. About 8 days see rain.

light clothessun protection

UV index in Sioux Falls 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 Sioux Falls peaks around June 16 at about 8 (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 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 16UV 8Dec 22UV 2
UV index (midday)Level
Jan2Low
Feb2Moderate
Mar4Moderate
Apr5High
May6High
Jun9Very high
Jul6High
Aug7High
Sep6High
Oct4Moderate
Nov2Moderate
Dec2Low
Location & terrain

Where is Sioux Falls?

Sioux Falls sits at 43.5°N, 96.7°W, 1,470 ft above sea level, in United States. The nearest listed city is Brookings, 53 mi away.

Topography around Sioux Falls

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

Within 2 miles, the terrain around Sioux Falls has only modest variations in elevation — a maximum elevation change of 246 ft around an average of 1,440 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 390 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 843 ft.

The land around Sioux Falls is covered by artificial surfaces (47%) and trees (37%) within 2 miles, cropland (51%) and grassland (25%) within 10 miles, and cropland (83%) within 50 miles.

2 miles
246 ft
10 miles
390 ft
50 miles
843 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Brookings 53 mi · Mitchell 66 mi · Sioux City 74 mi · Watertown 96 mi · Norfolk 111 mi · Willmar 137 mi · Mankato 142 mi · Fremont 146 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 Sioux Falls (43.5437°, -96.728°, elevation 1,470 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).