Boise weather in May: Boise, Idaho: normal highs, lows, rain and records for May
Boise in May has a normal high of 72°F and a normal low of 48°F, a daily mean of 60°F, rising from 67°F on the 1st to 76°F by the 31st. Measurable precipitation falls on 8 days in a normal May, 1.45 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 22°C and low of 9°C, 37 mm of precipitation in May.
- NOAA stationBoise Air Terminal
- Station IDUSW00024131
- Location43.57°N 116.24°W
- Elevation2,814 ft (858 m)
- From the center2 miles
- Population237,963
- Jan 39° 26°
- Feb 46° 29°
- Mar 56° 35°
- Apr 62° 40°
- May 72° 48°
- Jun 81° 54°
- Jul 93° 62°
- Aug 91° 61°
- Sep 80° 53°
- Oct 65° 42°
- Nov 49° 32°
- Dec 39° 25°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Boise in May?
The normal high is 72°F and the normal low 48°F, for a daily mean of 59.9°F. May is 9.0°F warmer than April and 7.9°F cooler than June. May is the 5th warmest month of the year in Boise and the 2nd wettest. Across the month the normal high rises 9°F, from 67°F on May 1 to 76°F on May 31. From one year to the next May's mean temperature typically moves about 2.7°F either way (NOAA's standard deviation), so roughly two Mays in three average between 57°F and 63°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 28%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| May 1 | 67°F | 43°F | 28% | 13% |
| May 8 | 70°F | 45°F | 28% | 13% |
| May 15 | 72°F | 48°F | 27% | 13% |
| May 22 | 74°F | 49°F | 26% | 12% |
| May 31 | 76°F | 51°F | 24% | 11% |
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 | 67°F | 43°F | 28% | 13% | 14 h 10 min |
| May 2 | 68°F | 44°F | 28% | 13% | 14 h 10 min |
| May 3 | 68°F | 44°F | 28% | 13% | 14 h 10 min |
| May 4 | 69°F | 44°F | 28% | 13% | 14 h 10 min |
| May 5 | 69°F | 44°F | 28% | 13% | 14 h 20 min |
| May 6 | 69°F | 45°F | 28% | 13% | 14 h 20 min |
| May 7 | 70°F | 45°F | 28% | 13% | 14 h 20 min |
| May 8 | 70°F | 45°F | 28% | 13% | 14 h 20 min |
| May 9 | 70°F | 46°F | 28% | 13% | 14 h 30 min |
| May 10 | 71°F | 46°F | 28% | 13% | 14 h 30 min |
| May 11 | 71°F | 46°F | 28% | 13% | 14 h 30 min |
| May 12 | 71°F | 47°F | 28% | 13% | 14 h 30 min |
| May 13 | 72°F | 47°F | 27% | 13% | 14 h 40 min |
| May 14 | 72°F | 47°F | 27% | 13% | 14 h 40 min |
| May 15 | 72°F | 48°F | 27% | 13% | 14 h 40 min |
| May 16 | 73°F | 48°F | 27% | 13% | 14 h 40 min |
| May 17 | 73°F | 48°F | 27% | 12% | 14 h 40 min |
| May 18 | 73°F | 48°F | 27% | 12% | 14 h 50 min |
| May 19 | 73°F | 49°F | 27% | 12% | 14 h 50 min |
| May 20 | 74°F | 49°F | 27% | 12% | 14 h 50 min |
| May 21 | 74°F | 49°F | 27% | 12% | 14 h 50 min |
| May 22 | 74°F | 49°F | 26% | 12% | 14 h 50 min |
| May 23 | 75°F | 50°F | 26% | 12% | 15 h |
| May 24 | 75°F | 50°F | 26% | 12% | 15 h |
| May 25 | 75°F | 50°F | 26% | 12% | 15 h |
| May 26 | 75°F | 50°F | 25% | 11% | 15 h |
| May 27 | 75°F | 50°F | 25% | 11% | 15 h |
| May 28 | 76°F | 51°F | 25% | 11% | 15 h 10 min |
| May 29 | 76°F | 51°F | 24% | 11% | 15 h 10 min |
| May 30 | 76°F | 51°F | 24% | 11% | 15 h 10 min |
| May 31 | 76°F | 51°F | 24% | 11% | 15 h 10 min |
- Normal high
- 72°FMay average
- Normal low
- 48°FMay average
- Precipitation
- 1.45 inmonth total
- Days with precipitation
- 80.01 inch or more
- Days at 90°F or more
- 1
- Nights at 32°F or colder
- 1
- Daylight
- 14 h 10 min to 15 h 10 minMay 1 to May 31
- Days at 70°F or more
- 18
- Days at 80°F or more
- 8
- Sunshine
- 81%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00024131; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Boise in May?
On a given May day the chance of 0.01 inch or more is 27% on average, highest around May 1 (28%). In all, 1.45 in falls on 8 days of a normal May.
In a normal May in Boise, 1 days reach 90°F and 1 nights fall to freezing.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00024131.
How humid and windy is Boise in May?
At 3 p.m. the normal temperature is 75°F with 28% relative humidity and a dew point of 39°F; at 6 a.m. it is 53°F with 65% humidity. The wind averages 8.0 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. | 53°F | 42°F | 65% | 5.7 mph | 68% |
| 9 a.m. | 62°F | 43°F | 49% | 7.5 mph | 71% |
| noon | 70°F | 41°F | 35% | 9.2 mph | 74% |
| 3 p.m. | 75°F | 39°F | 28% | 10.3 mph | 78% |
| 6 p.m. | 74°F | 38°F | 28% | 10.9 mph | 74% |
| 9 p.m. | 66°F | 41°F | 40% | 7.0 mph | 73% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00024131. 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 Boise?
The warmest May temperature on Boise's official record (since 1875) is 100°F, on May 29, 1897; the coldest is 22°F, on May 5, 1982. The wettest May brought 4.92 in (1896); the snowiest, 4.0 inches (1964).
The May mean against the 1991-2020 normal of 59.9°F: 2021 59.5°F (−0.4), 2022 55.5°F (−4.4), 2023 65.0°F (+5.1), 2024 58.2°F (−1.7), 2025 62.3°F (+2.4), 2026 63.7°F (+3.8). 3 of 6 ran warmer than normal.
| May | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 59.5°F | −0.4°F | 0.77 in |
| 2022 | 55.5°F | −4.4°F | 2.46 in |
| 2023 | 65.0°F | +5.1°F | 1.43 in |
| 2024 | 58.2°F | −1.7°F | 1.48 in |
| 2025 | 62.3°F | +2.4°F | 0.81 in |
| 2026 | 63.7°F | +3.8°F | 0.08 in |
Source: records: ACIS, NWS threaded record BOIthr; recent months: ACIS, station USW00024131. Records and recent months use complete months only.
How does May in Boise compare across Idaho?
Across the 85 places PlainClimate covers in Idaho, May normal highs run from 50°F in Mullan to 79°F in Glenns Ferry; Boise's is 72°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.