Bismarck, ND weather in September
Expect mild weather with some rain in Bismarck in September, with highs near 73°F and lows near 46°F. Rain falls on about 7 days. Good for outdoor plans.
- Normal high
- 73°F
- Normal low
- 46°F
- Wet days
- 7
- 1.7 in total
- Muggy days
- 0
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 79°F | 67°F |
| Normal low | 51°F | 40°F |
| Chance of a wet day | 25% | 23% |
| Sunrise / sunset | 7:02 am / 8:23 pm | 7:40 am / 7:25 pm |
| Daylight | 13.3 h | 11.8 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Central Time).
A typical September day
- 6 am49°Fdew point 45°F
- 9 am57°Fdew point 47°F
- Noon67°Fdew point 47°F
- 3 pm71°Fdew point 46°F
- 6 pm68°Fdew point 46°F
- 9 pm58°Fdew point 47°F
NOAA hourly normals (local standard time) from Bismarck (3 mi away); average wind 9 mph; clear or few clouds in 68% of daytime hours, mostly cloudy or overcast in 26%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F15 of 30
- Hot dayshigh 90°F or more2 of 30
- Muggy daysdaily mean dew point 65°F or more0 of 30
- Wet daysat least 0.01 in of rain or melted snow7 of 30
- Notable rainat least 0.10 in3 of 30
- Freezing nightslow 32°F or below2 of 30
- Snow on the groundsnow depth 1 in or more0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 1.7 in; a dry September brings about 0.8 in and a wet one about 2.2 in (25th and 75th percentiles). About 1 day brings half an inch or more.
How September varies from year to year
- Warmest September, 1991-20202015: average high 80°F
- Coolest September1999: average high 66°F
- Wettest September2019: 5.7 in
- Driest September2012: 0.05 in
- Highest reading103°F (September 5, 2001)
- Lowest reading20°F (September 22, 1995)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 84°F | 73°F | 57°F |
| Normal low | 56°F | 46°F | 33°F |
| Wet days | 8 | 7 | 7 |
| Comfortable days | 9 | 15 | 8 |
| Daylight | 14.2 h | 12.6 h | 10.9 h |
Highs change by -11°F from August and -16°F into October.
How Bismarck ranks in September
- Normal high313th warmest of 378 cities; 2nd of 4 in North Dakota
- Wet days168th driest of 378
- Comfortable days89th most of 342
What to pack for Bismarck in September
- Layers – afternoons near 73°F but nights near 46°F
Frost in September
The first fall frost typically comes around Sep 27; in 1 year in 10 it comes before Sep 15. All frost dates for Bismarck.
Heating and cooling
September has 204 heating degree days and 44 cooling degree days (base 65°F), 3% of the year's total heating and cooling demand.
Questions
How hot is Bismarck in September?
The normal high is 73°F and the normal low is 46°F. From 1991 to 2020 the hottest September reading was 103°F (September 5, 2001).
Does it rain a lot in Bismarck in September?
About 7 days in September have at least 0.01 in of precipitation, and the normal total is 1.7 in. The wettest September in 1991-2020 was in 2019 (5.7 in); the driest was in 2012 (0.05 in).
Is September a good time to visit Bismarck?
September ranks 3rd of 12 months on our comfort score for Bismarck (69 out of 100). It has about 15 comfortable days and about 2 days at 90°F or hotter. The best month is May.
Where the numbers come from
- Temperature, rain, snowfall, snow depth, frost dates, humidity and wind by hour and cloud cover: Bismarck (USW00024011), 2.8 mi SSE of the city center, 1,658 ft . NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Bismarck Municipal Airport (727640-24011), 2.2 mi SE of the city center, 1,651 ft . Hourly observations, 1991-2020.