Missoula, MT weather in September
September in Missoula: mild, with some rain. Highs 73°F, lows 42°F, rain on about 7 days. A great month for outdoor plans.
- Normal high
- 73°F
- Normal low
- 42°F
- Wet days
- 7
- 1.0 in total
- Muggy days
- 0
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 79°F | 66°F |
| Normal low | 47°F | 38°F |
| Chance of a wet day | 23% | 26% |
| Sunrise / sunset | 6:55 am / 8:16 pm | 7:33 am / 7:18 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 (Mountain Time).
A typical September day
- 6 am45°Fdew point 38°F
- 9 am53°Fdew point 40°F
- Noon64°Fdew point 40°F
- 3 pm71°Fdew point 38°F
- 6 pm68°Fdew point 39°F
- 9 pm57°Fdew point 40°F
NOAA hourly normals (local standard time) from Missoula Intl Airport (6 mi away); average wind 5 mph.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F14 of 30
- Hot dayshigh 90°F or more1 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 and snow in September
Normal precipitation is 1.0 in; a dry September brings about 0.3 in and a wet one about 1.5 in (25th and 75th percentiles). Days with half an inch or more are rare. Normal snowfall is 0.1 in.
How September varies from year to year
- Warmest September, 1991-20202011: average high 80°F
- Coolest September2004: average high 65°F
- Wettest September1995: 2.6 in
- Driest September2012: no measurable precipitation
- Highest reading97°F (September 2, 2017)
- Lowest reading20°F (September 23, 2000)
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 | 56°F |
| Normal low | 50°F | 42°F | 32°F |
| Wet days | 6 | 7 | 10 |
| Comfortable days | 7 | 14 | 6 |
| Daylight | 14.2 h | 12.6 h | 10.9 h |
Highs change by -11°F from August and -17°F into October.
Nearby alternatives in September
- Warmer: Boise, ID249 mi · high 80°F · 4 wet days
- Drier: Boise, ID249 mi · high 80°F · 4 wet days
How Missoula ranks in September
- Normal high323rd warmest of 378 cities; 2nd of 6 in Montana
- Wet days167th driest of 378
- Comfortable days95th most of 342
What to pack for Missoula in September
- Layers – afternoons near 73°F but nights near 42°F
Heating and cooling
September has 240 heating degree days and 15 cooling degree days (base 65°F), 3% of the year's total heating and cooling demand.
Questions
How hot is Missoula in September?
The normal high is 73°F and the normal low is 42°F. From 1991 to 2020 the hottest September reading was 97°F (September 2, 2017).
Does it rain a lot in Missoula in September?
About 7 days in September have at least 0.01 in of precipitation, and the normal total is 1.0 in. The wettest September in 1991-2020 was in 1995 (2.6 in); the driest was in 2012, with no measurable precipitation.
Does it snow in Missoula in September?
Yes. Normal snowfall in September is 0.1 in.
Is September a good time to visit Missoula?
September ranks 3rd of 12 months on our comfort score for Missoula (70 out of 100). It has about 14 comfortable days and about 1 day at 90°F or hotter. The best months are May and June.
Where the numbers come from
- Temperature, rain, snowfall, snow depth and humidity and wind by hour: Missoula Intl Airport (USW00024153), 5.7 mi NW of the city center, 3,192 ft . NOAA normals and daily records, 1991-2020.
- Frost dates: Missoula 2 Ne (USC00245735), 2.2 mi NE of the city center, 3,420 ft (212 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Missoula International Airport (727730-24153), 5.8 mi NW of the city center, 3,195 ft . Hourly observations, 1991-2020.
- Not available for this location: cloud cover (no station close enough or similar enough in elevation).