Great Falls weather in May: Great Falls, Montana: normal highs, lows, rain and records for May
Great Falls in May has a normal high of 65°F and a normal low of 38°F, a daily mean of 52°F, rising from 60°F on the 1st to 69°F by the 31st. Measurable precipitation falls on 11 days in a normal May, 2.43 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 18°C and low of 4°C, 62 mm of precipitation and 5 cm of snow in May.
- NOAA stationGreat Falls Airport
- Station IDUSW00024143
- Location47.47°N 111.38°W
- Elevation3,664 ft (1,117 m)
- From the center4 miles
- Population60,013
- Jan 35° 15°
- Feb 37° 15°
- Mar 46° 22°
- Apr 55° 30°
- May 65° 38°
- Jun 73° 46°
- Jul 84° 51°
- Aug 83° 50°
- Sep 72° 43°
- Oct 57° 33°
- Nov 44° 24°
- Dec 36° 16°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Great Falls in May?
The normal high is 65°F and the normal low 38°F, for a daily mean of 51.5°F. May is 9.1°F warmer than April and 7.9°F cooler than June. May is the 5th warmest month of the year in Great Falls and the 2nd wettest. Across the month the normal high rises 9°F, from 60°F on May 1 to 69°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 49°F and 54°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 | 60°F | 33°F | 34% | 16% |
| May 8 | 62°F | 36°F | 35% | 18% |
| May 15 | 65°F | 38°F | 37% | 20% |
| May 22 | 67°F | 41°F | 39% | 22% |
| May 31 | 69°F | 43°F | 41% | 23% |
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 | 60°F | 33°F | 34% | 16% | 14 h 20 min |
| May 2 | 60°F | 34°F | 34% | 16% | 14 h 30 min |
| May 3 | 60°F | 34°F | 34% | 16% | 14 h 30 min |
| May 4 | 61°F | 34°F | 34% | 17% | 14 h 30 min |
| May 5 | 61°F | 35°F | 34% | 17% | 14 h 40 min |
| May 6 | 62°F | 35°F | 35% | 17% | 14 h 40 min |
| May 7 | 62°F | 35°F | 35% | 17% | 14 h 40 min |
| May 8 | 62°F | 36°F | 35% | 18% | 14 h 50 min |
| May 9 | 63°F | 36°F | 35% | 18% | 14 h 50 min |
| May 10 | 63°F | 36°F | 35% | 18% | 14 h 50 min |
| May 11 | 63°F | 37°F | 36% | 18% | 14 h 50 min |
| May 12 | 64°F | 37°F | 36% | 19% | 15 h |
| May 13 | 64°F | 37°F | 36% | 19% | 15 h |
| May 14 | 64°F | 38°F | 37% | 19% | 15 h |
| May 15 | 65°F | 38°F | 37% | 20% | 15 h |
| May 16 | 65°F | 39°F | 37% | 20% | 15 h 10 min |
| May 17 | 65°F | 39°F | 38% | 20% | 15 h 10 min |
| May 18 | 66°F | 39°F | 38% | 21% | 15 h 10 min |
| May 19 | 66°F | 40°F | 38% | 21% | 15 h 10 min |
| May 20 | 66°F | 40°F | 39% | 22% | 15 h 20 min |
| May 21 | 66°F | 40°F | 39% | 22% | 15 h 20 min |
| May 22 | 67°F | 41°F | 39% | 22% | 15 h 20 min |
| May 23 | 67°F | 41°F | 40% | 23% | 15 h 20 min |
| May 24 | 67°F | 41°F | 40% | 23% | 15 h 30 min |
| May 25 | 67°F | 42°F | 40% | 23% | 15 h 30 min |
| May 26 | 68°F | 42°F | 40% | 23% | 15 h 30 min |
| May 27 | 68°F | 42°F | 40% | 23% | 15 h 30 min |
| May 28 | 68°F | 42°F | 41% | 23% | 15 h 30 min |
| May 29 | 68°F | 43°F | 41% | 23% | 15 h 40 min |
| May 30 | 68°F | 43°F | 41% | 23% | 15 h 40 min |
| May 31 | 69°F | 43°F | 41% | 23% | 15 h 40 min |
- Normal high
- 65°FMay average
- Normal low
- 38°FMay average
- Precipitation
- 2.43 inmonth total
- Days with precipitation
- 110.01 inch or more
- Snowfall
- 1.9 inmonth total
- Nights at 32°F or colder
- 6
- Daylight
- 14 h 20 min to 15 h 40 minMay 1 to May 31
- Days at 70°F or more
- 10
- Days at 80°F or more
- 3
- Sunshine
- 71%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00024143; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain or snow in Great Falls in May?
On a given May day the chance of 0.01 inch or more is 37% on average, highest around May 31 (41%). In all, 2.43 in falls on 11 days of a normal May.
In a normal May in Great Falls, 6 nights fall to freezing and snowfall averages 1.9 inches.
Snow falls on 1 day in a normal May, and an inch or more covers the ground on 1 day.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00024143.
How humid and windy is Great Falls in May?
At 3 p.m. the normal temperature is 66°F with 39% relative humidity and a dew point of 41°F; at 6 a.m. it is 49°F with 75% humidity. The wind averages 9.8 mph, most often from the west-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 | 75% | 8.1 mph | 56% |
| 9 a.m. | 58°F | 42°F | 55% | 10.2 mph | 60% |
| noon | 64°F | 41°F | 43% | 10.6 mph | 51% |
| 3 p.m. | 66°F | 41°F | 39% | 11.7 mph | 50% |
| 6 p.m. | 64°F | 41°F | 43% | 11.4 mph | 50% |
| 9 p.m. | 55°F | 42°F | 61% | 9.1 mph | 52% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00024143. 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 Great Falls?
The warmest May temperature on Great Falls's official record (since 1891) is 100°F, on May 28, 1919; the coldest is 12°F, on May 1, 2009. The wettest May brought 8.13 in (1953); the snowiest, 11.6 inches (1989).
The May mean against the 1991-2020 normal of 51.5°F: 2021 48.6°F (−2.9), 2022 50.2°F (−1.3), 2023 57.5°F (+6.0), 2024 49.7°F (−1.8), 2025 55.3°F (+3.8), 2026 54.7°F (+3.2). 3 of 6 ran warmer than normal.
| May | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 48.6°F | −2.9°F | 4.30 in |
| 2022 | 50.2°F | −1.3°F | 1.24 in |
| 2023 | 57.5°F | +6.0°F | 2.60 in |
| 2024 | 49.7°F | −1.8°F | 2.22 in |
| 2025 | 55.3°F | +3.8°F | 2.54 in |
| 2026 | 54.7°F | +3.2°F | 3.43 in |
Source: records: ACIS, NWS threaded record GTFthr; recent months: ACIS, station USW00024143. Records and recent months use complete months only.
How does May in Great Falls 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; Great Falls's is 65°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.