Big Sky weather in September: Big Sky, Montana: normal highs, lows, rain and records for September
Big Sky in September has a normal high of 68°F and a normal low of 33°F, a daily mean of 51°F, falling from 73°F on the 1st to 62°F by the 30th. Measurable precipitation falls on 10 days in a normal September, 1.70 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 20°C and low of 1°C, 43 mm of precipitation in September.
- NOAA stationBig Sky (2 mi WNW)
- Station IDUSC00240775
- Location45.28°N 111.33°W
- Elevation6,590 ft (2,009 m)
- Population (census place)2,388
- Jan 30° 9°
- Feb 34° 9°
- Mar 42° 17°
- Apr 48° 23°
- May 58° 30°
- Jun 67° 36°
- Jul 78° 41°
- Aug 77° 39°
- Sep 68° 33°
- Oct 53° 25°
- Nov 37° 16°
- Dec 28° 9°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Big Sky in September?
The normal high is 68°F and the normal low 33°F, for a daily mean of 50.8°F. September is 7.2°F cooler than August and 12.0°F warmer than October. September is the 4th warmest month of the year in Big Sky and the 8th wettest. Across the month the normal high falls 11°F, from 73°F on September 1 to 62°F on September 30. From one year to the next September's mean temperature typically moves about 1.8°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 49°F and 53°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 34%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 73°F | 36°F | 34% | 17% |
| September 8 | 71°F | 35°F | 33% | 17% |
| September 15 | 69°F | 34°F | 33% | 17% |
| September 22 | 66°F | 32°F | 32% | 16% |
| September 30 | 62°F | 30°F | 30% | 15% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 73°F | 36°F | 34% | 17% | 13 h 20 min |
| September 2 | 73°F | 36°F | 34% | 17% | 13 h 20 min |
| September 3 | 72°F | 36°F | 34% | 17% | 13 h 10 min |
| September 4 | 72°F | 36°F | 34% | 17% | 13 h 10 min |
| September 5 | 72°F | 36°F | 33% | 17% | 13 h 10 min |
| September 6 | 72°F | 35°F | 33% | 17% | 13 h |
| September 7 | 71°F | 35°F | 33% | 17% | 13 h |
| September 8 | 71°F | 35°F | 33% | 17% | 13 h |
| September 9 | 71°F | 35°F | 33% | 17% | 13 h |
| September 10 | 70°F | 35°F | 33% | 17% | 12 h 50 min |
| September 11 | 70°F | 35°F | 33% | 17% | 12 h 50 min |
| September 12 | 70°F | 34°F | 33% | 17% | 12 h 50 min |
| September 13 | 69°F | 34°F | 33% | 17% | 12 h 40 min |
| September 14 | 69°F | 34°F | 33% | 17% | 12 h 40 min |
| September 15 | 69°F | 34°F | 33% | 17% | 12 h 40 min |
| September 16 | 68°F | 34°F | 33% | 16% | 12 h 30 min |
| September 17 | 68°F | 33°F | 33% | 16% | 12 h 30 min |
| September 18 | 68°F | 33°F | 32% | 16% | 12 h 30 min |
| September 19 | 67°F | 33°F | 32% | 16% | 12 h 20 min |
| September 20 | 67°F | 33°F | 32% | 16% | 12 h 20 min |
| September 21 | 66°F | 32°F | 32% | 16% | 12 h 20 min |
| September 22 | 66°F | 32°F | 32% | 16% | 12 h 10 min |
| September 23 | 65°F | 32°F | 31% | 16% | 12 h 10 min |
| September 24 | 65°F | 32°F | 31% | 16% | 12 h 10 min |
| September 25 | 64°F | 31°F | 31% | 15% | 12 h 10 min |
| September 26 | 64°F | 31°F | 31% | 15% | 12 h |
| September 27 | 64°F | 31°F | 31% | 15% | 12 h |
| September 28 | 63°F | 30°F | 31% | 15% | 12 h |
| September 29 | 62°F | 30°F | 30% | 15% | 11 h 50 min |
| September 30 | 62°F | 30°F | 30% | 15% | 11 h 50 min |
- Normal high
- 68°FSeptember average
- Normal low
- 33°FSeptember average
- Precipitation
- 1.70 inmonth total
- Days with precipitation
- 100.01 inch or more
- Nights at 32°F or colder
- 15
- Daylight
- 13 h 20 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 17
- Days at 80°F or more
- 4
- Sunshine
- 79%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USC00240775; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Big Sky in September?
On a given September day the chance of 0.01 inch or more is 32% on average, highest around September 1 (34%). In all, 1.70 in falls on 10 days of a normal September.
In a normal September in Big Sky, 15 nights fall to freezing.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USC00240775.
What are the records for September in Big Sky?
The warmest September temperature on this station's record (since 1967) is 91°F, on September 5, 1967; the coldest is 5°F, on September 20, 1983. The wettest September brought 3.89 in (1972); the snowiest, 10.0 inches (1978).
Source: records: ACIS, station USC00240775. Records and recent months use complete months only.
How does September in Big Sky compare across Montana?
Across the 141 places PlainClimate covers in Montana, September normal highs run from 62°F in Cooke City to 79°F in Hardin; Big Sky's is 68°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.