Flathead County Weather in September
Average highs run from 76°F on September 1 to 62°F on September 30, and lows from 48°F to 40°F. Normal precipitation for the month is 2.21 in over about 8 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
- 69°F
- Average low
- 44°F
- Precipitation
- 2.21 in
- Record high
- 99°FSep 1, 1967
- Record low
- 7°FSep 24, 1926
- Chance of a freeze
- 42%
- Days of 90°F or more
- 0.5
- Daylight
- 13 h 23 min to 11 h 43 min
- Cloud cover
- 57%
- Humidity
- 65%
- Dew point
- 35°F
- Wind
- 4.7 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 | 76°F | 48°F | 99°F 1967 | 32°F 1999 | 23% | 0% |
| Sep 2 | 75°F | 47°F | 96°F 1998 | 29°F 1959 | 23% | 0% |
| Sep 3 | 75°F | 47°F | 97°F 1988 | 31°F 1974 | 23% | 0% |
| Sep 4 | 74°F | 47°F | 93°F 1998 | 27°F 1962 | 23% | 0% |
| Sep 5 | 74°F | 47°F | 94°F 1967 | 30°F 1956 | 24% | 0% |
| Sep 6 | 74°F | 46°F | 93°F 1998 | 27°F 1969 | 24% | 0% |
| Sep 7 | 73°F | 46°F | 93°F 2022 | 27°F 1992 | 24% | 0% |
| Sep 8 | 73°F | 46°F | 94°F 1958 | 23°F 2020 | 24% | 0% |
| Sep 9 | 72°F | 46°F | 92°F 1969 | 26°F 1959 | 25% | 0% |
| Sep 10 | 72°F | 45°F | 92°F 1969 | 27°F 1972 | 25% | 0% |
| Sep 11 | 71°F | 45°F | 92°F 1958 | 27°F 1921 | 25% | 0% |
| Sep 12 | 71°F | 45°F | 90°F 1959 | 23°F 2014 | 25% | 0% |
| Sep 13 | 71°F | 44°F | 86°F 1943 | 23°F 1970 | 26% | 0% |
| Sep 14 | 70°F | 44°F | 86°F 2013 | 16°F 1970 | 26% | 0% |
| Sep 15 | 70°F | 44°F | 89°F 1998 | 20°F 1970 | 26% | 0% |
| Sep 16 | 69°F | 44°F | 88°F 2009 | 23°F 1973 | 26% | 0% |
| Sep 17 | 69°F | 43°F | 89°F 1981 | 22°F 1973 | 27% | 0% |
| Sep 18 | 68°F | 43°F | 90°F 1981 | 22°F 1971 | 27% | 0% |
| Sep 19 | 68°F | 43°F | 85°F 2008 | 23°F 1983 | 27% | 0% |
| Sep 20 | 67°F | 43°F | 85°F 1922 | 21°F 1934 | 28% | 0% |
| Sep 21 | 67°F | 42°F | 87°F 1967 | 22°F 1971 | 28% | 0% |
| Sep 22 | 66°F | 42°F | 84°F 1905 | 22°F 2000 | 28% | 0% |
| Sep 23 | 66°F | 42°F | 87°F 2011 | 13°F 1926 | 28% | 0% |
| Sep 24 | 65°F | 41°F | 89°F 2014 | 7°F 1926 | 29% | 0% |
| Sep 25 | 65°F | 41°F | 88°F 2001 | 17°F 1926 | 29% | 0% |
| Sep 26 | 64°F | 41°F | 87°F 1952 | 24°F 1900 | 29% | 0% |
| Sep 27 | 64°F | 41°F | 86°F 1957 | 24°F 1985 | 29% | 0% |
| Sep 28 | 63°F | 40°F | 85°F 1967 | 18°F 1985 | 30% | 1% |
| Sep 29 | 62°F | 40°F | 82°F 1967 | 19°F 1985 | 30% | 1% |
| Sep 30 | 62°F | 40°F | 82°F 1963 | 22°F 1971 | 30% | 1% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (MDT).
- September 1
- sunrise 6:54 AM, sunset 8:17 PM
- September 30
- sunrise 7:34 AM, sunset 7:17 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00244328 (Hungry Horse Dam), public domain. Records: NOAA GHCN-Daily, station USC00244558, 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.