Spearfish Weather in September
Average highs run from 80°F on September 1 to 67°F on September 30, and lows from 53°F to 42°F. Normal precipitation for the month is 1.56 in over about 6 wet days.
September day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
September at a glance
- Average high
- 74°F
- Average low
- 48°F
- Precipitation
- 1.56 in
- Snowfall
- 0.1 in
- Record high
- 105°FSep 7, 1978
- Record low
- 15°FSep 25, 1926
- Chance of a freeze
- 38%
- Days of 90°F or more
- 3.1
- Daylight
- 13 h 14 min to 11 h 46 min
- Cloud cover
- 49%
- Humidity
- 52%
- Dew point
- 40°F
- Wind
- 7.8 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| Sep 1 | 80°F | 53°F | 102°F 1929 | 38°F 1965 | 20% | 0% |
| Sep 2 | 80°F | 52°F | 99°F 1945 | 38°F 1902 | 20% | 0% |
| Sep 3 | 79°F | 52°F | 99°F 2002 | 35°F 1974 | 20% | 0% |
| Sep 4 | 79°F | 52°F | 101°F 1960 | 30°F 1962 | 20% | 0% |
| Sep 5 | 79°F | 51°F | 97°F 2001 | 33°F 1902 | 20% | 0% |
| Sep 6 | 78°F | 51°F | 103°F 1978 | 34°F 1929 | 20% | 0% |
| Sep 7 | 78°F | 51°F | 105°F 1978 | 30°F 1929 | 20% | 0% |
| Sep 8 | 78°F | 51°F | 100°F 1959 | 29°F 1929 | 20% | 0% |
| Sep 9 | 77°F | 50°F | 98°F 1931 | 28°F 2020 | 21% | 0% |
| Sep 10 | 77°F | 50°F | 96°F 1979 | 29°F 1962 | 21% | 0% |
| Sep 11 | 77°F | 50°F | 96°F 1978 | 29°F 1921 | 21% | 1% |
| Sep 12 | 76°F | 49°F | 97°F 2004 | 30°F 1949 | 21% | 1% |
| Sep 13 | 76°F | 49°F | 95°F 1936 | 27°F 1904 | 21% | 1% |
| Sep 14 | 75°F | 48°F | 97°F 1948 | 28°F 1961 | 21% | 1% |
| Sep 15 | 75°F | 48°F | 99°F 1948 | 29°F 1903 | 21% | 1% |
| Sep 16 | 74°F | 48°F | 92°F 1908 | 27°F 1959 | 21% | 1% |
| Sep 17 | 74°F | 47°F | 95°F 1920 | 26°F 1965 | 21% | 1% |
| Sep 18 | 73°F | 47°F | 94°F 1914 | 26°F 1901 | 21% | 1% |
| Sep 19 | 73°F | 47°F | 93°F 2004 | 27°F 1965 | 21% | 1% |
| Sep 20 | 72°F | 46°F | 93°F 1937 | 25°F 1995 | 21% | 1% |
| Sep 21 | 72°F | 46°F | 93°F 1922 | 28°F 1934 | 21% | 1% |
| Sep 22 | 71°F | 45°F | 92°F 1936 | 22°F 1985 | 21% | 1% |
| Sep 23 | 71°F | 45°F | 92°F 1936 | 27°F 1965 | 21% | 2% |
| Sep 24 | 70°F | 44°F | 90°F 1938 | 20°F 1926 | 22% | 2% |
| Sep 25 | 70°F | 44°F | 95°F 2014 | 15°F 1926 | 22% | 2% |
| Sep 26 | 69°F | 44°F | 95°F 2014 | 20°F 1942 | 22% | 2% |
| Sep 27 | 68°F | 43°F | 93°F 1952 | 24°F 1951 | 22% | 2% |
| Sep 28 | 68°F | 43°F | 90°F 2010 | 21°F 1951 | 22% | 2% |
| Sep 29 | 67°F | 42°F | 92°F 2001 | 23°F 1959 | 22% | 2% |
| Sep 30 | 67°F | 42°F | 90°F 1963 | 21°F 1961 | 22% | 2% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (MDT).
- September 1
- sunrise 6:18 AM, sunset 7:32 PM
- September 30
- sunrise 6:52 AM, sunset 6:38 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00397882 (Spearfish), public domain. Records: NOAA GHCN-Daily, station USC00397882, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.