Bismarck weather in September

In September, Bismarck sees average daytime highs of 71°F and overnight lows near 48°F, with 1.8 in of rain across 6.5 wet days and about 12.4 hours of daylight. It is the 4th-warmest and 5th-wettest month of the year here.

Highs ease over the month, from about 77°F in the first days to 65°F by the end. The sky is clear or mostly clear about 46% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 12 min at the start of September to 11 h 30 min by month's end. Set against the rest of the year, September is Bismarck's 3rd-clearest and 9th-windiest month. For the whole year in context, see Bismarck's year-round climate.

Daytime high
71°
4th warmest
Overnight low
48°
9th coldest
Rainfall
1.8 in
6.5 wet days
Daylight
12 h 18 min
6:28 AM – 6:47 PM
Cloud cover
46%
3rd clearest
Wind
9 mph
9th windiest
Solar energy
4.33 kWh/m²
Travel score
7.2
out of 10

Bismarck is capital city of the U.S. state of North Dakota and seat of Burleigh County.

Density
58,300/km²
people per km²
Founded
1872

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 77°F in the first days to 65°F by the end.

A typical September day in Bismarck reaches about 71°F in the afternoon and slips back to 48°F overnight — a 23°F spread between the day's warmth and the night's chill. On most days the high lands between 57°F and 84°F. Set against its neighbours, September runs about 10°F cooler than August and about 15°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
17854
27753
37753
47653
57652
67552
77551
87451
97450
107350
117349
127249
137249
147148
157148
167047
177047
186947
196946
206946
216845
226845
236744
246744
256644
266643
276543
286542
296442
306442

How September really feels in Bismarck

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.

Bismarck weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan22° / 0.64.54.88.80.0
Feb26° / 0.74.44.6100.0
Mar38° / 20°1.05411.60.2
Apr53° / 32°1.87.52.913.33.1
May66° / 44°2.99.80.414.85.9
Jun75° / 55°3.811.1015.66.7
Jul81° / 60°3.09.8015.36.8
Aug81° / 57°2.37.40147.2
Sep71° / 48°1.86.5012.47.2
Oct55° / 35°1.86.51.510.64.0
Nov38° / 22°0.84.13.59.20.2
Dec26° / 10°0.74.44.98.40.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 46% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 14% of September, with mostly cloudy or overcast conditions the remaining 39%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16832
26733
36634
46634
56535
66436
76436
86337
96337
106238
116139
126139
136040
145941
155941
165941
175941
185842
195941
205941
215941
225941
235941
245842
255842
265842
275842
285842
295842
305842

Chance of precipitation in September

Any precipitation

Bismarck gets around 1.8 in of rain over 6.5 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 22% and peaks near 23% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
122
222
322
422
522
622
722
823
923
1023
1123
1223
1323
1423
1523
1623
1723
1823
1923
2022
2122
2222
2321
2421
2521
2621
2721
2821
2920
3020

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 83% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
15924143
26223132
36422122
46621112
56820102
6711991
7721981
8741871
9761761
10771661
11791551
12801550
13821440
14831340
15851230
16861130
17871120
18881020
1989920
2090820
2192710
2293610
2393610
2494510
2595410
2695410
2797300
2897300
2998200
3098200

Wind in September

Winds average 9 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
89light breeze
99light breeze
109light breeze
119light breeze
129light breeze
139light breeze
149light breeze
159light breeze
169light breeze
179light breeze
189light 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 h 12 min at the start of September to 11 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 102 minutes over September. Sunrise moves from 6:08 AM to 6:47 AM, and sunset from 7:18 PM to 6:18 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.26:087:18
213.16:097:16
313.16:107:14
413.06:127:12
513.06:137:10
612.96:147:08
712.86:167:06
812.86:177:04
912.76:187:02
1012.76:207:00
1112.66:216:58
1212.66:226:56
1312.56:246:54
1412.46:256:52
1512.46:266:49
1612.36:286:47
1712.36:296:45
1812.26:306:43
1912.26:326:41
2012.16:336:39
2112.06:346:37
2212.06:366:35
2311.96:376:33
2411.96:386:31
2511.86:406:29
2611.86:416:27
2711.76:426:24
2811.66:446:22
2911.66:456:20
3011.56:476:18

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.33 kWh/m².

For context, solar energy here swings from a low near 1.43 kWh/m² to a high of 6.7 kWh/m² in July across the year — September's 4.33 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.1Bright
25.1Bright
35.0Bright
44.9Bright
54.9Bright
64.8Bright
74.8Bright
84.7Bright
94.7Bright
104.6Bright
114.5Bright
124.5Bright
134.4Bright
144.4Bright
154.3Bright
164.3Bright
174.2Bright
184.2Bright
194.1Bright
204.1Bright
214.0Bright
224.0Moderate
233.9Moderate
243.9Moderate
253.9Moderate
263.8Moderate
273.8Moderate
283.7Moderate
293.6Moderate
303.6Moderate
Planning a trip in September

Hazard calendar for Bismarck

In seasonPeak

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

Bismarck'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 Bismarck?

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
4.6
Beach & pool
4th-best month of the year

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

What to pack for Bismarck in September

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

In September, Bismarck sees daytime highs around 71°F and nights near 48°F. Little to plan around — just the basics. About 7 days see rain.

UV index in Bismarck in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Bismarck peaks around June 22 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 20 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 22UV 8Dec 20UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar3Moderate
Apr4Moderate
May6High
Jun8Very high
Jul8Very high
Aug6High
Sep5High
Oct4Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Bismarck?

Bismarck sits at 46.8°N, 100.8°W, 1,686 ft above sea level, in United States. The nearest listed city is Mandan, 5.0 mi away.

Topography around Bismarck

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

Within 2 miles, the terrain around Bismarck has only modest variations in elevation — a maximum elevation change of 285 ft around an average of 1,713 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 505 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 915 ft.

The land around Bismarck is covered by artificial surfaces (54%) and trees (23%) within 2 miles, grassland (63%) and cropland (20%) within 10 miles, and grassland (62%) and cropland (34%) within 50 miles.

2 miles
285 ft
10 miles
505 ft
50 miles
915 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Mandan 5.0 mi · Dickinson 95 mi · Jamestown 98 mi · Minot 101 mi · Aberdeen 144 mi · Williston 162 mi · West Fargo 183 mi · Fargo 189 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 Bismarck (46.8083°, -100.7837°, elevation 1,686 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).