Helena weather in May

In May, Helena sees average daytime highs of 59°F and overnight lows near 37°F, with 3.2 in of precipitation across 13.8 wet days and about 14.8 hours of daylight. It is the 5th-warmest and 2nd-wettest month of the year here.

Highs climb over the month, from about 54°F in the first days to 63°F by the end. The sky is clear or mostly clear about 17% of the time in May, and the air most often feels dry.

Daylight stretches from about 14 h 06 min at the start of May to 15 h 18 min by month's end. Set against the rest of the year, May is Helena's 10th-clearest and 8th-windiest month. For the whole year in context, see Helena's year-round climate.

Daytime high: 59°; 5th warmest
Overnight low: 37°; 8th coldest
Precipitation: 3.2 in; 13.8 wet days
Daylight: 14 h 48 min; 5:00 AM – 7:48 PM
Cloud cover: 66%; 10th clearest
Wind: 5 mph; 8th windiest
Solar energy: 6.38 kWh/m²
Travel score: 4.0; out of 10

Helena is capital city of the U.S. state of Montana and seat of Lewis and Clark County.

Density: 749/km²; people per km²
Founded: 1864

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

← April Helena year-round climate June →Best places to visit in May

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

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 54°F in the first days to 63°F by the end.

A typical May day in Helena reaches about 59°F in the afternoon and slips back to 37°F overnight — a 22°F spread between the day's warmth and the night's chill. On most days the high lands between 46°F and 72°F. Set against its neighbours, May runs about 10°F warmer than April and about 9°F cooler than June.

	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	31
Avg high (°F)	53	54	54	55	55	55	56	56	56	57	57	58	58	58	59	59	59	60	60	60	60	61	61	61	62	62	62	62	63	63	63
Avg low (°F)	32	32	32	33	33	33	34	34	34	35	35	35	36	36	37	37	37	38	38	38	38	39	39	39	40	40	40	40	40	41	41

	Avg high (°F)	Avg low (°F)
1	53	32
2	54	32
3	54	32
4	55	33
5	55	33
6	55	33
7	56	34
8	56	34
9	56	34
10	57	35
11	57	35
12	58	35
13	58	36
14	58	36
15	59	37
16	59	37
17	59	37
18	60	38
19	60	38
20	60	38
21	60	38
22	61	39
23	61	39
24	61	39
25	62	40
26	62	40
27	62	40
28	62	40
29	63	40
30	63	41
31	63	41

How May really feels in Helena

Once humidity and wind are folded in, May averages 0 days that feel above 90°F and 14 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 May is cold — wind chill drags the overnight "feels like" below the raw low.

Helena weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 2nd-wettest month here — the current month is highlighted below.

Month	High / Low (°F)	Rainfall (inches)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	28° / 12°	0.9	7	7.6	8.8	0.0
Feb	31° / 13°	0.9	7	7.6	10	0.0
Mar	39° / 20°	1.4	9.7	7.7	11.6	0.1
Apr	48° / 28°	2.4	11.9	7.2	13.3	1.7
May	59° / 37°	3.2	13.8	2.7	14.8	4.0
Jun	67° / 44°	3.8	13.5	0.6	15.6	5.7
Jul	78° / 50°	1.7	8.8	0	15.2	7.2
Aug	78° / 49°	1.5	7.5	0.1	14	7.4
Sep	67° / 42°	1.6	6.8	0.9	12.4	6.7
Oct	52° / 32°	1.5	8.3	3.8	10.7	2.9
Nov	37° / 21°	1.2	7.7	6.2	9.2	0.1
Dec	27° / 12°	1.1	7.3	7.8	8.4	0.0

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 17% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 20% of May, with mostly cloudy or overcast conditions the remaining 63%.

	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	31
Clearer (%)	41	41	41	41	41	42	41	40	40	38	38	37	37	36	35	35	35	34	34	35	34	34	34	36	35	35	35	36	36	37	37
Cloudier (%)	59	59	59	59	59	58	59	60	60	62	62	63	63	64	65	65	65	66	66	65	66	66	66	64	65	65	65	64	64	63	63

	Clearer (%)	Cloudier (%)
1	41	59
2	41	59
3	41	59
4	41	59
5	41	59
6	42	58
7	41	59
8	40	60
9	40	60
10	38	62
11	38	62
12	37	63
13	37	63
14	36	64
15	35	65
16	35	65
17	35	65
18	34	66
19	34	66
20	35	65
21	34	66
22	34	66
23	34	66
24	36	64
25	35	65
26	35	65
27	35	65
28	36	64
29	36	64
30	37	63
31	37	63

Chance of precipitation in May

Any precipitationSnow

Helena gets around 3.2 in of rain and snow over 13.8 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 45% and peaks near 51% on the wettest days, and about 3 days bring snow. The odds climb toward the end of the month.

	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	31
Rain chance (%)	38	38	38	38	38	38	39	39	40	41	42	43	44	45	46	47	48	48	49	50	51	51	51	51	51	50	50	50	49	49	49
Snow chance (%)	16	15	15	14	14	13	12	11	11	10	10	10	9	9	9	9	8	8	8	8	8	7	7	7	7	7	7	7	6	6	6

	Rain chance (%)	Snow chance (%)
1	38	16
2	38	15
3	38	15
4	38	14
5	38	14
6	38	13
7	39	12
8	39	11
9	40	11
10	41	10
11	42	10
12	43	10
13	44	9
14	45	9
15	46	9
16	47	9
17	48	8
18	48	8
19	49	8
20	50	8
21	51	8
22	51	7
23	51	7
24	51	7
25	51	7
26	50	7
27	50	7
28	50	7
29	49	6
30	49	6
31	49	6

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May 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	31
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	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
31	100

Wind in May

Winds average 5 mph in May.

Across May, 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	31
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	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	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
31	5	calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 14 h 06 min at the start of May to 15 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 72 minutes over May. Sunrise moves from 5:22 AM to 4:46 AM, and sunset from 7:29 PM to 8:05 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	31
Daylight (h)	14.1	14.2	14.2	14.3	14.3	14.4	14.4	14.5	14.5	14.5	14.6	14.6	14.7	14.7	14.8	14.8	14.8	14.9	14.9	15.0	15.0	15.0	15.1	15.1	15.1	15.2	15.2	15.2	15.3	15.3	15.3
Sunrise (AM)	5:22	5:20	5:19	5:17	5:16	5:14	5:13	5:11	5:10	5:08	5:07	5:06	5:04	5:03	5:02	5:00	4:59	4:58	4:57	4:56	4:55	4:54	4:53	4:52	4:51	4:50	4:49	4:48	4:47	4:47	4:46
Sunset (PM)	7:29	7:30	7:32	7:33	7:34	7:36	7:37	7:38	7:39	7:41	7:42	7:43	7:45	7:46	7:47	7:48	7:50	7:51	7:52	7:53	7:54	7:56	7:57	7:58	7:59	8:00	8:01	8:02	8:03	8:04	8:05

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	14.1	5:22	7:29
2	14.2	5:20	7:30
3	14.2	5:19	7:32
4	14.3	5:17	7:33
5	14.3	5:16	7:34
6	14.4	5:14	7:36
7	14.4	5:13	7:37
8	14.5	5:11	7:38
9	14.5	5:10	7:39
10	14.5	5:08	7:41
11	14.6	5:07	7:42
12	14.6	5:06	7:43
13	14.7	5:04	7:45
14	14.7	5:03	7:46
15	14.8	5:02	7:47
16	14.8	5:00	7:48
17	14.8	4:59	7:50
18	14.9	4:58	7:51
19	14.9	4:57	7:52
20	15.0	4:56	7:53
21	15.0	4:55	7:54
22	15.0	4:54	7:56
23	15.1	4:53	7:57
24	15.1	4:52	7:58
25	15.1	4:51	7:59
26	15.2	4:50	8:00
27	15.2	4:49	8:01
28	15.2	4:48	8:02
29	15.3	4:47	8:03
30	15.3	4:47	8:04
31	15.3	4:46	8:05

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 6.38 kWh/m².

For context, solar energy here swings from a low near 1.55 kWh/m² to a high of 7.45 kWh/m² in July across the year — May's 6.38 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	31
Solar energy (kWh/m²)	6.2	6.2	6.2	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.3	6.4	6.4	6.4	6.4	6.4	6.5	6.5	6.5	6.5	6.5
Level	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense	Intense

	Solar energy (kWh/m²)	Level
1	6.2	Intense
2	6.2	Intense
3	6.2	Intense
4	6.3	Intense
5	6.3	Intense
6	6.3	Intense
7	6.3	Intense
8	6.3	Intense
9	6.3	Intense
10	6.3	Intense
11	6.3	Intense
12	6.3	Intense
13	6.3	Intense
14	6.3	Intense
15	6.3	Intense
16	6.3	Intense
17	6.3	Intense
18	6.3	Intense
19	6.3	Intense
20	6.3	Intense
21	6.3	Intense
22	6.4	Intense
23	6.4	Intense
24	6.4	Intense
25	6.4	Intense
26	6.4	Intense
27	6.5	Intense
28	6.5	Intense
29	6.5	Intense
30	6.5	Intense
31	6.5	Intense

Planning a trip in May

Hazard calendar for Helena

In seasonPeak

In May, Helena sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Helena's rainy season runs April–June, when most of the year's rain falls.

Rainy season

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Is May a good time to visit Helena?

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

4.0

Sightseeing

5th-best month of the year

0.4

Beach & pool

5th-best month of the year

May is a reasonable time to visit Helena for sightseeing.

What to pack for Helena in May

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

In May, Helena sees daytime highs around 59°F and nights near 37°F. Pack rain gear and sun protection. Worth having: a warm layer. About 14 days see rain.

rain gearsun protectiona warm layer

UV index in Helena in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Helena peaks around July 15 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	3	2	1
Level	Low	Low	Moderate	Moderate	High	Very high	Very high	Very high	High	Moderate	Low	Low

	UV index (midday)	Level
Jan	1	Low
Feb	2	Low
Mar	5	Moderate
Apr	5	Moderate
May	7	High
Jun	8	Very high
Jul	9	Very high
Aug	7	Very high
Sep	5	High
Oct	3	Moderate
Nov	2	Low
Dec	1	Low

Air quality in Helena in May

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Helena is worst in August — around 25 µg/m³ PM2.5 (moderate), about 3.1× the cleanest month (December, 8 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)	9	9	11	11	11	9	23	25	17	8	9	8
Level	Good	Good	Good	Good	Good	Good	Moderate	Moderate	Moderate	Good	Good	Good

	PM2.5 (µg/m³)	Level
Jan	9	Good
Feb	9	Good
Mar	11	Good
Apr	11	Good
May	11	Good
Jun	9	Good
Jul	23	Moderate
Aug	25	Moderate
Sep	17	Moderate
Oct	8	Good
Nov	9	Good
Dec	8	Good

Location & terrain

Where is Helena?

Helena sits at 46.6°N, 112.0°W, 4,058 ft above sea level, in United States. The nearest listed city is Butte, 47 mi away.

Topography around Helena

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

Within 2 miles, the terrain around Helena has significant variations in elevation — a maximum elevation change of 1,588 ft around an average of 4,219 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,481 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 6,729 ft.

The land around Helena is covered by artificial surfaces (45%), trees (28%) and grassland (25%) within 2 miles, grassland (53%) and trees (31%) within 10 miles, and grassland (53%) and trees (42%) within 50 miles.

2 miles

1,588 ft

artificial surfaces 45%

10 miles

3,481 ft

grassland 53%

50 miles

6,729 ft

grassland 53%

treesgrasslandcroplandartificial surfacesbare terrainwater

← April Helena year-round climate June →Best places to visit in May

May weather nearby: Butte 47 mi · Great Falls 71 mi · Bozeman 79 mi · Missoula 94 mi · Kalispell 153 mi · Whitefish 165 mi · Billings 178 mi · Rexburg 191 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 Helena (46.5927°, -112.0361°, elevation 4,058 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	53	32
2	54	32
3	54	32
4	55	33
5	55	33
6	55	33
7	56	34
8	56	34
9	56	34
10	57	35
11	57	35
12	58	35
13	58	36
14	58	36
15	59	37
16	59	37
17	59	37
18	60	38
19	60	38
20	60	38
21	60	38
22	61	39
23	61	39
24	61	39
25	62	40
26	62	40
27	62	40
28	62	40
29	63	40
30	63	41
31	63	41

	Clearer (%)	Cloudier (%)
1	41	59
2	41	59
3	41	59
4	41	59
5	41	59
6	42	58
7	41	59
8	40	60
9	40	60
10	38	62
11	38	62
12	37	63
13	37	63
14	36	64
15	35	65
16	35	65
17	35	65
18	34	66
19	34	66
20	35	65
21	34	66
22	34	66
23	34	66
24	36	64
25	35	65
26	35	65
27	35	65
28	36	64
29	36	64
30	37	63
31	37	63

	Rain chance (%)	Snow chance (%)
1	38	16
2	38	15
3	38	15
4	38	14
5	38	14
6	38	13
7	39	12
8	39	11
9	40	11
10	41	10
11	42	10
12	43	10
13	44	9
14	45	9
15	46	9
16	47	9
17	48	8
18	48	8
19	49	8
20	50	8
21	51	8
22	51	7
23	51	7
24	51	7
25	51	7
26	50	7
27	50	7
28	50	7
29	49	6
30	49	6
31	49	6

	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
31	100

	Avg high (°F)	Avg low (°F)
1	53	32
2	54	32
3	54	32
4	55	33
5	55	33
6	55	33
7	56	34
8	56	34
9	56	34
10	57	35
11	57	35
12	58	35
13	58	36
14	58	36
15	59	37
16	59	37
17	59	37
18	60	38
19	60	38
20	60	38
21	60	38
22	61	39
23	61	39
24	61	39
25	62	40
26	62	40
27	62	40
28	62	40
29	63	40
30	63	41
31	63	41

	Clearer (%)	Cloudier (%)
1	41	59
2	41	59
3	41	59
4	41	59
5	41	59
6	42	58
7	41	59
8	40	60
9	40	60
10	38	62
11	38	62
12	37	63
13	37	63
14	36	64
15	35	65
16	35	65
17	35	65
18	34	66
19	34	66
20	35	65
21	34	66
22	34	66
23	34	66
24	36	64
25	35	65
26	35	65
27	35	65
28	36	64
29	36	64
30	37	63
31	37	63

	Rain chance (%)	Snow chance (%)
1	38	16
2	38	15
3	38	15
4	38	14
5	38	14
6	38	13
7	39	12
8	39	11
9	40	11
10	41	10
11	42	10
12	43	10
13	44	9
14	45	9
15	46	9
16	47	9
17	48	8
18	48	8
19	49	8
20	50	8
21	51	8
22	51	7
23	51	7
24	51	7
25	51	7
26	50	7
27	50	7
28	50	7
29	49	6
30	49	6
31	49	6

	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
31	100

	Avg high (°F)	Avg low (°F)
1	53	32
2	54	32
3	54	32
4	55	33
5	55	33
6	55	33
7	56	34
8	56	34
9	56	34
10	57	35
11	57	35
12	58	35
13	58	36
14	58	36
15	59	37
16	59	37
17	59	37
18	60	38
19	60	38
20	60	38
21	60	38
22	61	39
23	61	39
24	61	39
25	62	40
26	62	40
27	62	40
28	62	40
29	63	40
30	63	41
31	63	41

	Clearer (%)	Cloudier (%)
1	41	59
2	41	59
3	41	59
4	41	59
5	41	59
6	42	58
7	41	59
8	40	60
9	40	60
10	38	62
11	38	62
12	37	63
13	37	63
14	36	64
15	35	65
16	35	65
17	35	65
18	34	66
19	34	66
20	35	65
21	34	66
22	34	66
23	34	66
24	36	64
25	35	65
26	35	65
27	35	65
28	36	64
29	36	64
30	37	63
31	37	63

	Rain chance (%)	Snow chance (%)
1	38	16
2	38	15
3	38	15
4	38	14
5	38	14
6	38	13
7	39	12
8	39	11
9	40	11
10	41	10
11	42	10
12	43	10
13	44	9
14	45	9
15	46	9
16	47	9
17	48	8
18	48	8
19	49	8
20	50	8
21	51	8
22	51	7
23	51	7
24	51	7
25	51	7
26	50	7
27	50	7
28	50	7
29	49	6
30	49	6
31	49	6

	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
31	100