Lewistown weather in May: Lewistown, Montana: normal highs, lows, rain and records for May
Lewistown in May has a normal high of 63°F and a normal low of 37°F, a daily mean of 50°F, rising from 58°F on the 1st to 67°F by the 31st. Measurable precipitation falls on 14 days in a normal May, 2.88 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 17°C and low of 3°C, 73 mm of precipitation in May.
- NOAA stationLewistown Municipal Airport
- Station IDUSW00024036
- Location47.05°N 109.46°W
- Elevation4,145 ft (1,263 m)
- Population6,204
- Jan 34° 13°
- Feb 35° 14°
- Mar 44° 21°
- Apr 53° 29°
- May 63° 37°
- Jun 71° 45°
- Jul 82° 51°
- Aug 81° 50°
- Sep 70° 42°
- Oct 56° 31°
- Nov 43° 21°
- Dec 35° 14°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Lewistown in May?
The normal high is 63°F and the normal low 37°F, for a daily mean of 50.0°F. May is 9.1°F warmer than April and 8.0°F cooler than June. May is the 5th warmest month of the year in Lewistown and the 2nd wettest. Across the month the normal high rises 9°F, from 58°F on May 1 to 67°F on May 31. From one year to the next May's mean temperature typically moves about 2.6°F either way (NOAA's standard deviation), so roughly two Mays in three average between 47°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 48%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| May 1 | 58°F | 32°F | 41% | 19% |
| May 8 | 60°F | 35°F | 43% | 21% |
| May 15 | 63°F | 37°F | 45% | 23% |
| May 22 | 65°F | 40°F | 47% | 26% |
| May 31 | 67°F | 42°F | 48% | 27% |
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 | 58°F | 32°F | 41% | 19% | 14 h 20 min |
| May 2 | 58°F | 33°F | 42% | 20% | 14 h 30 min |
| May 3 | 58°F | 33°F | 42% | 20% | 14 h 30 min |
| May 4 | 59°F | 33°F | 42% | 20% | 14 h 30 min |
| May 5 | 59°F | 34°F | 42% | 20% | 14 h 30 min |
| May 6 | 59°F | 34°F | 42% | 21% | 14 h 40 min |
| May 7 | 60°F | 34°F | 43% | 21% | 14 h 40 min |
| May 8 | 60°F | 35°F | 43% | 21% | 14 h 40 min |
| May 9 | 60°F | 35°F | 43% | 22% | 14 h 50 min |
| May 10 | 61°F | 35°F | 43% | 22% | 14 h 50 min |
| May 11 | 61°F | 36°F | 44% | 22% | 14 h 50 min |
| May 12 | 62°F | 36°F | 44% | 22% | 14 h 50 min |
| May 13 | 62°F | 36°F | 44% | 23% | 15 h |
| May 14 | 62°F | 37°F | 44% | 23% | 15 h |
| May 15 | 63°F | 37°F | 45% | 23% | 15 h |
| May 16 | 63°F | 38°F | 45% | 24% | 15 h |
| May 17 | 63°F | 38°F | 45% | 24% | 15 h 10 min |
| May 18 | 64°F | 38°F | 46% | 25% | 15 h 10 min |
| May 19 | 64°F | 39°F | 46% | 25% | 15 h 10 min |
| May 20 | 64°F | 39°F | 46% | 25% | 15 h 10 min |
| May 21 | 64°F | 39°F | 46% | 26% | 15 h 20 min |
| May 22 | 65°F | 40°F | 47% | 26% | 15 h 20 min |
| May 23 | 65°F | 40°F | 47% | 26% | 15 h 20 min |
| May 24 | 65°F | 40°F | 47% | 26% | 15 h 20 min |
| May 25 | 65°F | 41°F | 47% | 27% | 15 h 20 min |
| May 26 | 66°F | 41°F | 47% | 27% | 15 h 30 min |
| May 27 | 66°F | 41°F | 47% | 27% | 15 h 30 min |
| May 28 | 66°F | 42°F | 48% | 27% | 15 h 30 min |
| May 29 | 66°F | 42°F | 48% | 27% | 15 h 30 min |
| May 30 | 67°F | 42°F | 48% | 27% | 15 h 30 min |
| May 31 | 67°F | 42°F | 48% | 27% | 15 h 40 min |
- Normal high
- 63°FMay average
- Normal low
- 37°FMay average
- Precipitation
- 2.88 inmonth total
- Days with precipitation
- 140.01 inch or more
- Nights at 32°F or colder
- 8
- Daylight
- 14 h 20 min to 15 h 40 minMay 1 to May 31
- Days at 70°F or more
- 8
- Days at 80°F or more
- 2
- Sunshine
- 72%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00024036; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Lewistown in May?
On a given May day the chance of 0.01 inch or more is 45% on average, highest around May 30 (48%). In all, 2.88 in falls on 14 days of a normal May.
In a normal May in Lewistown, 8 nights fall to freezing.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00024036.
How humid and windy is Lewistown in May?
At 3 p.m. the normal temperature is 63°F with 44% relative humidity and a dew point of 41°F; at 6 a.m. it is 47°F with 77% humidity. The wind averages 9.0 mph, most often from the north-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. | 47°F | 41°F | 77% | 6.9 mph | – |
| 9 a.m. | 57°F | 41°F | 55% | 9.2 mph | – |
| noon | 62°F | 41°F | 46% | 10.8 mph | – |
| 3 p.m. | 63°F | 41°F | 44% | 11.0 mph | – |
| 6 p.m. | 61°F | 42°F | 49% | 10.0 mph | – |
| 9 p.m. | 53°F | 42°F | 67% | 8.2 mph | – |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00024036. 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 Lewistown?
The warmest May temperature on this station's record (since 1896) is 98°F, on May 14, 1931; the coldest is 11°F, on May 6, 1929. The wettest May brought 9.16 in (1981); the snowiest, 29.5 inches (1982).
The May mean against the 1991-2020 normal of 50.0°F: 2021 47.5°F (−2.5), 2022 47.9°F (−2.1), 2023 55.7°F (+5.7), 2024 46.7°F (−3.3), 2025 52.8°F (+2.8), 2026 52.1°F (+2.1). 3 of 6 ran warmer than normal.
| May | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 47.5°F | −2.5°F | 2.27 in |
| 2022 | 47.9°F | −2.1°F | 1.70 in |
| 2023 | 55.7°F | +5.7°F | 3.02 in |
| 2024 | 46.7°F | −3.3°F | 3.86 in |
| 2025 | 52.8°F | +2.8°F | 2.89 in |
| 2026 | 52.1°F | +2.1°F | 2.36 in |
Source: records: ACIS, station USW00024036; recent months: ACIS, station USW00024036. Records and recent months use complete months only.
How does May in Lewistown 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; Lewistown's is 63°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.