Helena weather in May: Helena, Montana: normal highs, lows, rain and records for May
Helena in May has a normal high of 66°F and a normal low of 42°F, a daily mean of 54°F, rising from 62°F on the 1st to 70°F by the 31st. Measurable precipitation falls on 11 days in a normal May, 1.95 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 19°C and low of 5°C, 50 mm of precipitation and 0 cm of snow in May.
- NOAA stationHelena Regional Airport
- Station IDUSW00024144
- Location46.61°N 111.96°W
- Elevation3,828 ft (1,167 m)
- From the center3 miles
- Population34,729
- Jan 32° 14°
- Feb 37° 17°
- Mar 48° 25°
- Apr 57° 32°
- May 66° 42°
- Jun 75° 49°
- Jul 86° 55°
- Aug 85° 53°
- Sep 73° 45°
- Oct 58° 34°
- Nov 43° 23°
- Dec 33° 14°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Helena in May?
The normal high is 66°F and the normal low 42°F, for a daily mean of 53.9°F. May is 9.4°F warmer than April and 7.8°F cooler than June. May is the 5th warmest month of the year in Helena and the 2nd wettest. Across the month the normal high rises 8°F, from 62°F on May 1 to 70°F on May 31. From one year to the next May's mean temperature typically moves about 2.5°F either way (NOAA's standard deviation), so roughly two Mays in three average between 51°F and 56°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 41%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| May 1 | 62°F | 37°F | 31% | 13% |
| May 8 | 64°F | 39°F | 33% | 14% |
| May 15 | 66°F | 41°F | 36% | 17% |
| May 22 | 68°F | 44°F | 39% | 19% |
| May 31 | 70°F | 46°F | 41% | 21% |
Every day of May: normal high, low and chance of precipitation (warmest afternoon May 31, coldest night May 1)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| May 1 | 62°F | 37°F | 31% | 13% | 14 h 20 min |
| May 2 | 62°F | 37°F | 31% | 13% | 14 h 20 min |
| May 3 | 62°F | 37°F | 31% | 13% | 14 h 30 min |
| May 4 | 63°F | 38°F | 32% | 13% | 14 h 30 min |
| May 5 | 63°F | 38°F | 32% | 14% | 14 h 30 min |
| May 6 | 63°F | 38°F | 32% | 14% | 14 h 30 min |
| May 7 | 64°F | 39°F | 33% | 14% | 14 h 40 min |
| May 8 | 64°F | 39°F | 33% | 14% | 14 h 40 min |
| May 9 | 64°F | 39°F | 34% | 15% | 14 h 40 min |
| May 10 | 65°F | 40°F | 34% | 15% | 14 h 50 min |
| May 11 | 65°F | 40°F | 34% | 15% | 14 h 50 min |
| May 12 | 65°F | 40°F | 35% | 16% | 14 h 50 min |
| May 13 | 66°F | 41°F | 35% | 16% | 14 h 50 min |
| May 14 | 66°F | 41°F | 36% | 16% | 15 h |
| May 15 | 66°F | 41°F | 36% | 17% | 15 h |
| May 16 | 67°F | 42°F | 37% | 17% | 15 h |
| May 17 | 67°F | 42°F | 37% | 18% | 15 h |
| May 18 | 67°F | 42°F | 37% | 18% | 15 h 10 min |
| May 19 | 68°F | 43°F | 38% | 18% | 15 h 10 min |
| May 20 | 68°F | 43°F | 38% | 19% | 15 h 10 min |
| May 21 | 68°F | 43°F | 39% | 19% | 15 h 10 min |
| May 22 | 68°F | 44°F | 39% | 19% | 15 h 10 min |
| May 23 | 69°F | 44°F | 39% | 20% | 15 h 20 min |
| May 24 | 69°F | 44°F | 40% | 20% | 15 h 20 min |
| May 25 | 69°F | 44°F | 40% | 20% | 15 h 20 min |
| May 26 | 69°F | 45°F | 40% | 20% | 15 h 20 min |
| May 27 | 70°F | 45°F | 41% | 21% | 15 h 20 min |
| May 28 | 70°F | 45°F | 41% | 21% | 15 h 30 min |
| May 29 | 70°F | 45°F | 41% | 21% | 15 h 30 min |
| May 30 | 70°F | 46°F | 41% | 21% | 15 h 30 min |
| May 31 | 70°F | 46°F | 41% | 21% | 15 h 30 min |
- Normal high
- 66°FMay average
- Normal low
- 42°FMay average
- Precipitation
- 1.95 inmonth total
- Days with precipitation
- 110.01 inch or more
- Snowfall
- 0.1 inmonth total
- Nights at 32°F or colder
- 3
- Daylight
- 14 h 20 min to 15 h 30 minMay 1 to May 31
- Days at 70°F or more
- 12
- Days at 80°F or more
- 4
- Sunshine
- 69%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00024144; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain or snow in Helena in May?
On a given May day the chance of 0.01 inch or more is 36% on average, highest around May 31 (41%). In all, 1.95 in falls on 11 days of a normal May.
In a normal May in Helena, 3 nights fall to freezing and snowfall averages 0.1 inches.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00024144.
How humid and windy is Helena in May?
At 3 p.m. the normal temperature is 68°F with 36% relative humidity and a dew point of 40°F; at 6 a.m. it is 49°F with 71% humidity. The wind averages 7.7 mph, most often from the northwest in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 49°F | 41°F | 71% | 4.2 mph | 56% |
| 9 a.m. | 57°F | 41°F | 55% | 6.2 mph | 56% |
| noon | 65°F | 40°F | 41% | 9.4 mph | 54% |
| 3 p.m. | 68°F | 40°F | 36% | 12.0 mph | 50% |
| 6 p.m. | 65°F | 40°F | 40% | 11.1 mph | 47% |
| 9 p.m. | 58°F | 41°F | 54% | 7.4 mph | 51% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00024144. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for May in Helena?
The warmest May temperature on Helena's official record (since 1880) is 95°F, on May 28, 1919; the coldest is 17°F, on May 2, 1954. The wettest May brought 6.67 in (1927); the snowiest, 13.9 inches (1927).
The May mean against the 1991-2020 normal of 53.9°F: 2021 51.9°F (−2.0), 2022 52.5°F (−1.4), 2023 60.5°F (+6.6), 2024 53.0°F (−0.9), 2025 57.4°F (+3.5), 2026 55.7°F (+1.8). 3 of 6 ran warmer than normal.
| May | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 51.9°F | −2.0°F | 2.26 in |
| 2022 | 52.5°F | −1.4°F | 1.14 in |
| 2023 | 60.5°F | +6.6°F | 1.21 in |
| 2024 | 53.0°F | −0.9°F | 1.69 in |
| 2025 | 57.4°F | +3.5°F | 3.64 in |
| 2026 | 55.7°F | +1.8°F | 1.82 in |
Source: records: ACIS, NWS threaded record HLNthr; recent months: ACIS, station USW00024144. Records and recent months use complete months only.
How does May in Helena compare across Montana?
Across the 141 places PlainClimate covers in Montana, May normal highs run from 54°F in Cooke City to 72°F in Savage; Helena's is 66°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.