Butte weather in September

In September, Butte sees average daytime highs of 65°F and overnight lows near 38°F, with 1.4 in of precipitation across 6.6 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 70°F in the first days to 59°F by the end. The sky is clear or mostly clear about 42% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 06 min at the start of September to 11 h 30 min by month's end. Set against the rest of the year, September is Butte's 3rd-clearest and 9th-windiest month. For the whole year in context, see Butte's year-round climate.

Daytime high: 65°; 4th warmest
Overnight low: 38°; 9th coldest
Precipitation: 1.4 in; 6.6 wet days
Daylight: 12 h 18 min; 6:15 AM – 6:34 PM
Cloud cover: 47%; 3rd clearest
Wind: 5 mph; 9th windiest
Solar energy: 4.86 kWh/m²
Travel score: 6.3; out of 10

Butte is consolidated city-county (with Silver Bow County) in Montana, United States.

Density: 18/km²; people per km²
Founded: 1864

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

← August Butte year-round climate October →Best places to visit in September

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 70°F in the first days to 59°F by the end.

A typical September day in Butte reaches about 65°F in the afternoon and slips back to 38°F overnight — a 27°F spread between the day's warmth and the night's chill. On most days the high lands between 50°F and 77°F. Set against its neighbours, September runs about 11°F cooler than August and about 15°F warmer than October.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Avg high (°F)	71	71	71	70	69	69	69	68	67	67	67	66	65	65	65	64	64	63	63	63	62	62	62	61	61	60	60	59	59	58
Avg low (°F)	42	42	42	41	41	41	40	40	40	39	39	39	38	38	38	38	37	37	37	37	36	36	36	35	35	35	34	34	34	33

	Avg high (°F)	Avg low (°F)
1	71	42
2	71	42
3	71	42
4	70	41
5	69	41
6	69	41
7	69	40
8	68	40
9	67	40
10	67	39
11	67	39
12	66	39
13	65	38
14	65	38
15	65	38
16	64	38
17	64	37
18	63	37
19	63	37
20	63	37
21	62	36
22	62	36
23	62	36
24	61	35
25	61	35
26	60	35
27	60	34
28	59	34
29	59	34
30	58	33

How September really feels in Butte

Once humidity and wind are folded in, September averages 0 days that feel above 90°F and 10 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F

heat index over the day's high

Days feeling ≤ 32°F

wind chill below the day's low

The story in September is cold — wind chill drags the overnight "feels like" below the raw low.

Butte weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 6th-wettest month here — the current month is highlighted below.

Month	High / Low (°F)	Rainfall (inches)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	27° / 9°	0.9	6.9	8.1	8.9	0.0
Feb	30° / 11°	0.9	6.9	8.1	10	0.0
Mar	38° / 17°	1.4	9.8	9.4	11.6	0.0
Apr	45° / 24°	2.2	11.7	9	13.3	1.0
May	56° / 33°	3.1	14.8	4.2	14.7	3.2
Jun	65° / 40°	3.3	13.8	1.3	15.5	5.3
Jul	76° / 46°	1.5	8.6	0.1	15.2	7.3
Aug	76° / 45°	1.1	7	0.1	14	7.7
Sep	65° / 38°	1.4	6.6	1	12.3	6.3
Oct	49° / 28°	1.3	8.2	4.5	10.7	2.3
Nov	35° / 16°	1.2	7.6	7.3	9.2	0.0
Dec	26° / 7°	1.0	7.4	8.6	8.5	0.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 42% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 21% of September, with mostly cloudy or overcast conditions the remaining 38%.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Clearer (%)	69	68	67	66	66	65	65	64	62	62	61	60	60	59	59	60	60	60	60	60	60	61	61	61	61	62	62	60	60	60
Cloudier (%)	31	32	33	34	34	35	35	36	38	38	39	40	40	41	41	40	40	40	40	40	40	39	39	39	39	38	38	40	40	40

	Clearer (%)	Cloudier (%)
1	69	31
2	68	32
3	67	33
4	66	34
5	66	34
6	65	35
7	65	35
8	64	36
9	62	38
10	62	38
11	61	39
12	60	40
13	60	40
14	59	41
15	59	41
16	60	40
17	60	40
18	60	40
19	60	40
20	60	40
21	60	40
22	61	39
23	61	39
24	61	39
25	61	39
26	62	38
27	62	38
28	60	40
29	60	40
30	60	40

Chance of precipitation in September

Any precipitationSnow

Butte gets around 1.4 in of rain and snow over 6.6 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 23% and peaks near 24% on the wettest days, and about 1 day brings snow.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Rain chance (%)	21	21	21	22	22	22	22	22	23	23	24	24	24	24	24	23	23	23	22	22	22	22	22	22	22	22	22	23	23	23
Snow chance (%)	1	1	1	1	1	1	2	2	2	2	2	3	3	3	3	4	4	4	4	4	4	5	5	5	5	6	6	7	7	8

	Rain chance (%)	Snow chance (%)
1	21	1
2	21	1
3	21	1
4	22	1
5	22	1
6	22	1
7	22	2
8	22	2
9	23	2
10	23	2
11	24	2
12	24	3
13	24	3
14	24	3
15	24	3
16	23	4
17	23	4
18	23	4
19	22	4
20	22	4
21	22	4
22	22	5
23	22	5
24	22	5
25	22	5
26	22	6
27	22	6
28	23	7
29	23	7
30	23	8

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Dry (%)	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100

Wind in September

Winds average 5 mph in September.

Across September, daily wind ranges from about 5 mph on the calmest days to 5 mph at its breeziest. It stays fairly steady from day to day.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Wind speed (mph)	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5
Feels	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm

	Wind speed (mph)	Feels
1	5	calm
2	5	calm
3	5	calm
4	5	calm
5	5	calm
6	5	calm
7	5	calm
8	5	calm
9	5	calm
10	5	calm
11	5	calm
12	5	calm
13	5	calm
14	5	calm
15	5	calm
16	5	calm
17	5	calm
18	5	calm
19	5	calm
20	5	calm
21	5	calm
22	5	calm
23	5	calm
24	5	calm
25	5	calm
26	5	calm
27	5	calm
28	5	calm
29	5	calm
30	5	calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 06 min at the start of September to 11 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 96 minutes over September. Sunrise moves from 5:56 AM to 6:33 AM, and sunset from 7:04 PM to 6:06 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Daylight (h)	13.1	13.1	13.0	13.0	12.9	12.9	12.8	12.8	12.7	12.7	12.6	12.5	12.5	12.4	12.4	12.3	12.3	12.2	12.2	12.1	12.0	12.0	11.9	11.9	11.8	11.8	11.7	11.7	11.6	11.5
Sunrise (AM)	5:56	5:57	5:58	5:59	6:01	6:02	6:03	6:05	6:06	6:07	6:08	6:10	6:11	6:12	6:14	6:15	6:16	6:17	6:19	6:20	6:21	6:23	6:24	6:25	6:27	6:28	6:29	6:31	6:32	6:33
Sunset (PM)	7:04	7:02	7:00	6:58	6:56	6:54	6:52	6:50	6:48	6:46	6:44	6:42	6:40	6:38	6:36	6:34	6:32	6:30	6:28	6:26	6:24	6:22	6:20	6:18	6:16	6:14	6:12	6:10	6:08	6:06

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	13.1	5:56	7:04
2	13.1	5:57	7:02
3	13.0	5:58	7:00
4	13.0	5:59	6:58
5	12.9	6:01	6:56
6	12.9	6:02	6:54
7	12.8	6:03	6:52
8	12.8	6:05	6:50
9	12.7	6:06	6:48
10	12.7	6:07	6:46
11	12.6	6:08	6:44
12	12.5	6:10	6:42
13	12.5	6:11	6:40
14	12.4	6:12	6:38
15	12.4	6:14	6:36
16	12.3	6:15	6:34
17	12.3	6:16	6:32
18	12.2	6:17	6:30
19	12.2	6:19	6:28
20	12.1	6:20	6:26
21	12.0	6:21	6:24
22	12.0	6:23	6:22
23	11.9	6:24	6:20
24	11.9	6:25	6:18
25	11.8	6:27	6:16
26	11.8	6:28	6:14
27	11.7	6:29	6:12
28	11.7	6:31	6:10
29	11.6	6:32	6:08
30	11.5	6:33	6:06

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.86 kWh/m².

For context, solar energy here swings from a low near 1.6 kWh/m² to a high of 7.42 kWh/m² in July across the year — September's 4.86 kWh/m² falls in the middle.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Solar energy (kWh/m²)	5.7	5.6	5.6	5.5	5.5	5.4	5.3	5.3	5.2	5.1	5.1	5.0	4.9	4.9	4.8	4.8	4.7	4.7	4.6	4.6	4.5	4.5	4.4	4.4	4.3	4.3	4.2	4.2	4.1	4.1
Level	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright

	Solar energy (kWh/m²)	Level
1	5.7	Bright
2	5.6	Bright
3	5.6	Bright
4	5.5	Bright
5	5.5	Bright
6	5.4	Bright
7	5.3	Bright
8	5.3	Bright
9	5.2	Bright
10	5.1	Bright
11	5.1	Bright
12	5.0	Bright
13	4.9	Bright
14	4.9	Bright
15	4.8	Bright
16	4.8	Bright
17	4.7	Bright
18	4.7	Bright
19	4.6	Bright
20	4.6	Bright
21	4.5	Bright
22	4.5	Bright
23	4.4	Bright
24	4.4	Bright
25	4.3	Bright
26	4.3	Bright
27	4.2	Bright
28	4.2	Bright
29	4.1	Bright
30	4.1	Bright

Planning a trip in September

Is September a good time to visit Butte?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

6.3

Sightseeing

3rd-best month of the year

2.4

Beach & pool

3rd-best month of the year

September is a reasonable time to visit Butte for sightseeing.

What to pack for Butte in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Butte sees daytime highs around 65°F and nights near 38°F. Worth packing: a warm layer and sun protection. About 7 days see rain.

a warm layersun protection

UV index in Butte in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Butte peaks around July 14 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	1	2	5	5	7	8	9	7	5	4	2	1
Level	Low	Moderate	Moderate	Moderate	Very high	Very high	Very high	High	High	Moderate	Low	Low

	UV index (midday)	Level
Jan	1	Low
Feb	2	Moderate
Mar	5	Moderate
Apr	5	Moderate
May	7	Very high
Jun	8	Very high
Jul	9	Very high
Aug	7	High
Sep	5	High
Oct	4	Moderate
Nov	2	Low
Dec	1	Low

Air quality in Butte in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Butte is worst in September — around 30 µg/m³ PM2.5 (moderate), about 4.8× the cleanest month (January, 6 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
PM2.5 (µg/m³)	6	7	10	10	10	9	16	21	30	9	7	8
Level	Good	Good	Good	Good	Good	Good	Moderate	Moderate	Moderate	Good	Good	Good

	PM2.5 (µg/m³)	Level
Jan	6	Good
Feb	7	Good
Mar	10	Good
Apr	10	Good
May	10	Good
Jun	9	Good
Jul	16	Moderate
Aug	21	Moderate
Sep	30	Moderate
Oct	9	Good
Nov	7	Good
Dec	8	Good

Location & terrain

Where is Butte?

Butte sits at 46.0°N, 112.5°W, 5,538 ft above sea level, in United States. The nearest listed city is Helena, 47 mi away.

Topography around Butte

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Butte.

Within 2 miles, the terrain around Butte has significant variations in elevation — a maximum elevation change of 1,060 ft around an average of 5,617 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,494 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 7,228 ft.

The land around Butte is covered by artificial surfaces (40%) and grassland (36%) within 2 miles, trees (49%) and grassland (43%) within 10 miles, and trees (48%) and grassland (46%) within 50 miles.

2 miles

1,060 ft

artificial surfaces 40%

10 miles

3,494 ft

trees 49%

50 miles

7,228 ft

trees 48%

treesgrasslandcroplandartificial surfacesbare terrainwatermoss and lichen

← August Butte year-round climate October →Best places to visit in September

September weather nearby: Helena 47 mi · Bozeman 75 mi · Missoula 92 mi · Great Falls 119 mi · Rexburg 155 mi · Kalispell 173 mi · Idaho Falls 177 mi · Whitefish 186 mi

United States travel facts

Power plugs: Type A / B; 120 V · 60 Hz
Prices: ≈ 100% of US; price level, 2025
GDP per capita: $90,027; 2025
Happiness: 6.8 / 10; World Happiness, 2025
Safe drinking water: 98%; of population, 2024
Homicide rate: 5.8; per 100k, 2023
Road deaths: 12.7; per 100k/yr, 2019
Income group: High; World Bank
Religion

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Butte (46.0038°, -112.5347°, elevation 5,538 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).

	Avg high (°F)	Avg low (°F)
1	71	42
2	71	42
3	71	42
4	70	41
5	69	41
6	69	41
7	69	40
8	68	40
9	67	40
10	67	39
11	67	39
12	66	39
13	65	38
14	65	38
15	65	38
16	64	38
17	64	37
18	63	37
19	63	37
20	63	37
21	62	36
22	62	36
23	62	36
24	61	35
25	61	35
26	60	35
27	60	34
28	59	34
29	59	34
30	58	33

	Clearer (%)	Cloudier (%)
1	69	31
2	68	32
3	67	33
4	66	34
5	66	34
6	65	35
7	65	35
8	64	36
9	62	38
10	62	38
11	61	39
12	60	40
13	60	40
14	59	41
15	59	41
16	60	40
17	60	40
18	60	40
19	60	40
20	60	40
21	60	40
22	61	39
23	61	39
24	61	39
25	61	39
26	62	38
27	62	38
28	60	40
29	60	40
30	60	40

	Rain chance (%)	Snow chance (%)
1	21	1
2	21	1
3	21	1
4	22	1
5	22	1
6	22	1
7	22	2
8	22	2
9	23	2
10	23	2
11	24	2
12	24	3
13	24	3
14	24	3
15	24	3
16	23	4
17	23	4
18	23	4
19	22	4
20	22	4
21	22	4
22	22	5
23	22	5
24	22	5
25	22	5
26	22	6
27	22	6
28	23	7
29	23	7
30	23	8

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100

	Avg high (°F)	Avg low (°F)
1	71	42
2	71	42
3	71	42
4	70	41
5	69	41
6	69	41
7	69	40
8	68	40
9	67	40
10	67	39
11	67	39
12	66	39
13	65	38
14	65	38
15	65	38
16	64	38
17	64	37
18	63	37
19	63	37
20	63	37
21	62	36
22	62	36
23	62	36
24	61	35
25	61	35
26	60	35
27	60	34
28	59	34
29	59	34
30	58	33

	Clearer (%)	Cloudier (%)
1	69	31
2	68	32
3	67	33
4	66	34
5	66	34
6	65	35
7	65	35
8	64	36
9	62	38
10	62	38
11	61	39
12	60	40
13	60	40
14	59	41
15	59	41
16	60	40
17	60	40
18	60	40
19	60	40
20	60	40
21	60	40
22	61	39
23	61	39
24	61	39
25	61	39
26	62	38
27	62	38
28	60	40
29	60	40
30	60	40

	Rain chance (%)	Snow chance (%)
1	21	1
2	21	1
3	21	1
4	22	1
5	22	1
6	22	1
7	22	2
8	22	2
9	23	2
10	23	2
11	24	2
12	24	3
13	24	3
14	24	3
15	24	3
16	23	4
17	23	4
18	23	4
19	22	4
20	22	4
21	22	4
22	22	5
23	22	5
24	22	5
25	22	5
26	22	6
27	22	6
28	23	7
29	23	7
30	23	8

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100

	Avg high (°F)	Avg low (°F)
1	71	42
2	71	42
3	71	42
4	70	41
5	69	41
6	69	41
7	69	40
8	68	40
9	67	40
10	67	39
11	67	39
12	66	39
13	65	38
14	65	38
15	65	38
16	64	38
17	64	37
18	63	37
19	63	37
20	63	37
21	62	36
22	62	36
23	62	36
24	61	35
25	61	35
26	60	35
27	60	34
28	59	34
29	59	34
30	58	33

	Clearer (%)	Cloudier (%)
1	69	31
2	68	32
3	67	33
4	66	34
5	66	34
6	65	35
7	65	35
8	64	36
9	62	38
10	62	38
11	61	39
12	60	40
13	60	40
14	59	41
15	59	41
16	60	40
17	60	40
18	60	40
19	60	40
20	60	40
21	60	40
22	61	39
23	61	39
24	61	39
25	61	39
26	62	38
27	62	38
28	60	40
29	60	40
30	60	40

	Rain chance (%)	Snow chance (%)
1	21	1
2	21	1
3	21	1
4	22	1
5	22	1
6	22	1
7	22	2
8	22	2
9	23	2
10	23	2
11	24	2
12	24	3
13	24	3
14	24	3
15	24	3
16	23	4
17	23	4
18	23	4
19	22	4
20	22	4
21	22	4
22	22	5
23	22	5
24	22	5
25	22	5
26	22	6
27	22	6
28	23	7
29	23	7
30	23	8

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100