Thief River Falls Weather in September
Average highs run from 75°F on September 1 to 63°F on September 30, and lows from 52°F to 41°F.
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
- 69°F
- Average low
- 47°F
- Record high
- 96°FSep 1, 1921
- Record low
- 15°FSep 18, 1929
- Chance of a freeze
- 60%
- Days of 90°F or more
- 0.5
- Daylight
- 13 h 23 min to 11 h 43 min
- Cloud cover
- 61%
- Humidity
- 67%
- Dew point
- 46°F
- Wind
- 11.0 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 | 75°F | 52°F | 96°F 1921 | 33°F 1946 | 0% | |
| Sep 2 | 75°F | 52°F | 96°F 1983 | 29°F 1917 | 0% | |
| Sep 3 | 74°F | 51°F | 95°F 2023 | 32°F 1974 | 0% | |
| Sep 4 | 74°F | 51°F | 94°F 1922 | 30°F 1914 | 0% | |
| Sep 5 | 74°F | 51°F | 96°F 1978 | 32°F 1924 | 0% | |
| Sep 6 | 73°F | 50°F | 95°F 1976 | 32°F 1956 | 0% | |
| Sep 7 | 73°F | 50°F | 93°F 1976 | 33°F 1986 | 0% | |
| Sep 8 | 73°F | 50°F | 95°F 1978 | 30°F 1956 | ||
| Sep 9 | 72°F | 49°F | 92°F 1978 | 31°F 1917 | ||
| Sep 10 | 72°F | 49°F | 95°F 1952 | 28°F 1917 | ||
| Sep 11 | 71°F | 49°F | 93°F 1952 | 25°F 1955 | ||
| Sep 12 | 71°F | 48°F | 88°F 1952 | 29°F 1937 | ||
| Sep 13 | 70°F | 48°F | 93°F 1927 | 22°F 1923 | ||
| Sep 14 | 70°F | 47°F | 89°F 1927 | 27°F 1956 | ||
| Sep 15 | 70°F | 47°F | 87°F 1923 | 28°F 1984 | ||
| Sep 16 | 69°F | 47°F | 93°F 2025 | 25°F 1973 | ||
| Sep 17 | 69°F | 46°F | 91°F 1920 | 23°F 1959 | ||
| Sep 18 | 68°F | 46°F | 88°F 1989 | 15°F 1929 | ||
| Sep 19 | 68°F | 45°F | 89°F 1970 | 25°F 1929 | ||
| Sep 20 | 67°F | 45°F | 88°F 1970 | 24°F 1918 | ||
| Sep 21 | 67°F | 45°F | 89°F 1922 | 25°F 1934 | ||
| Sep 22 | 67°F | 44°F | 95°F 1922 | 15°F 1913 | ||
| Sep 23 | 66°F | 44°F | 89°F 2007 | 23°F 1913 | ||
| Sep 24 | 66°F | 44°F | 85°F 1990 | 25°F 1942 | ||
| Sep 25 | 65°F | 43°F | 89°F 1938 | 22°F 1985 | ||
| Sep 26 | 65°F | 43°F | 87°F 1974 | 19°F 1984 | ||
| Sep 27 | 64°F | 42°F | 89°F 1952 | 21°F 1935 | ||
| Sep 28 | 64°F | 42°F | 85°F 1970 | 21°F 1942 | ||
| Sep 29 | 63°F | 42°F | 90°F 2025 | 19°F 1984 | ||
| Sep 30 | 63°F | 41°F | 89°F 2025 | 22°F 1934 |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (CDT).
- September 1
- sunrise 6:43 AM, sunset 8:06 PM
- September 30
- sunrise 7:23 AM, sunset 7:06 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00218247 (Thief Rvr Falls 2), public domain. Records: NOAA GHCN-Daily, station USC00216787, 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 2026-09-25. Sun and moon: computed with the NOAA solar equations and Meeus.