Boston weather in May: Boston, Massachusetts: normal highs, lows, rain and records for May
Boston in May has a normal high of 67°F and a normal low of 50°F, a daily mean of 58°F, rising from 62°F on the 1st to 71°F by the 31st. Measurable precipitation falls on 12 days in a normal May, 3.25 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 19°C and low of 10°C, 83 mm of precipitation in May.
- NOAA stationBoston Logan International Airport
- Station IDUSW00014739
- Location42.36°N 71.01°W
- Elevation12 ft (4 m)
- From the center2 miles
- Population673,458
- Jan 37° 23°
- Feb 39° 25°
- Mar 46° 31°
- Apr 56° 41°
- May 67° 50°
- Jun 76° 60°
- Jul 82° 66°
- Aug 80° 65°
- Sep 73° 58°
- Oct 62° 48°
- Nov 52° 38°
- Dec 42° 29°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Boston in May?
The normal high is 67°F and the normal low 50°F, for a daily mean of 58.4°F. May is 9.8°F warmer than April and 9.6°F cooler than June. May is the 5th warmest month of the year in Boston and the 10th wettest. Across the month the normal high rises 9°F, from 62°F on May 1 to 71°F on May 31. From one year to the next May's mean temperature typically moves about 2.4°F either way (NOAA's standard deviation), so roughly two Mays in three average between 56°F and 61°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 39%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| May 1 | 62°F | 46°F | 39% | 22% |
| May 8 | 64°F | 48°F | 39% | 22% |
| May 15 | 66°F | 50°F | 38% | 23% |
| May 22 | 68°F | 52°F | 38% | 23% |
| May 31 | 71°F | 55°F | 37% | 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 | 62°F | 46°F | 39% | 22% | 14 h |
| May 2 | 63°F | 46°F | 39% | 22% | 14 h |
| May 3 | 63°F | 47°F | 39% | 22% | 14 h 10 min |
| May 4 | 63°F | 47°F | 39% | 22% | 14 h 10 min |
| May 5 | 63°F | 47°F | 39% | 22% | 14 h 10 min |
| May 6 | 64°F | 48°F | 39% | 22% | 14 h 10 min |
| May 7 | 64°F | 48°F | 39% | 22% | 14 h 20 min |
| May 8 | 64°F | 48°F | 39% | 22% | 14 h 20 min |
| May 9 | 65°F | 48°F | 38% | 22% | 14 h 20 min |
| May 10 | 65°F | 49°F | 38% | 22% | 14 h 20 min |
| May 11 | 65°F | 49°F | 38% | 22% | 14 h 30 min |
| May 12 | 65°F | 49°F | 38% | 22% | 14 h 30 min |
| May 13 | 66°F | 50°F | 38% | 22% | 14 h 30 min |
| May 14 | 66°F | 50°F | 38% | 22% | 14 h 30 min |
| May 15 | 66°F | 50°F | 38% | 23% | 14 h 30 min |
| May 16 | 67°F | 50°F | 38% | 23% | 14 h 40 min |
| May 17 | 67°F | 51°F | 38% | 23% | 14 h 40 min |
| May 18 | 67°F | 51°F | 38% | 23% | 14 h 40 min |
| May 19 | 67°F | 51°F | 38% | 23% | 14 h 40 min |
| May 20 | 68°F | 51°F | 38% | 23% | 14 h 40 min |
| May 21 | 68°F | 52°F | 38% | 23% | 14 h 50 min |
| May 22 | 68°F | 52°F | 38% | 23% | 14 h 50 min |
| May 23 | 68°F | 52°F | 38% | 23% | 14 h 50 min |
| May 24 | 69°F | 53°F | 38% | 23% | 14 h 50 min |
| May 25 | 69°F | 53°F | 37% | 23% | 14 h 50 min |
| May 26 | 69°F | 53°F | 37% | 23% | 14 h 50 min |
| May 27 | 70°F | 53°F | 37% | 23% | 15 h |
| May 28 | 70°F | 54°F | 37% | 23% | 15 h |
| May 29 | 70°F | 54°F | 37% | 23% | 15 h |
| May 30 | 71°F | 54°F | 37% | 23% | 15 h |
| May 31 | 71°F | 55°F | 37% | 23% | 15 h |
- Normal high
- 67°FMay average
- Normal low
- 50°FMay average
- Precipitation
- 3.25 inmonth total
- Days with precipitation
- 120.01 inch or more
- Days at 90°F or more
- 1
- Daylight
- 14 h to 15 hMay 1 to May 31
- Days at 70°F or more
- 12
- Days at 80°F or more
- 4
- Sunshine
- 68%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00014739; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Boston in May?
On a given May day the chance of 0.01 inch or more is 38% on average, highest around May 1 (39%). In all, 3.25 in falls on 12 days of a normal May, 1 of them with an inch or more.
In a normal May in Boston, 1 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00014739.
How humid and windy is Boston in May?
At 3 p.m. the normal temperature is 68°F with 57% relative humidity and a dew point of 52°F; at 6 a.m. it is 59°F with 76% humidity. The wind averages 10.8 mph, most often from the east-southeast in the afternoon.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 59°F | 51°F | 76% | 9.4 mph | – |
| 9 a.m. | 64°F | 52°F | 64% | 10.8 mph | – |
| noon | 67°F | 52°F | 58% | 13.0 mph | – |
| 3 p.m. | 68°F | 52°F | 57% | 13.7 mph | – |
| 6 p.m. | 65°F | 51°F | 60% | 11.8 mph | – |
| 9 p.m. | 62°F | 52°F | 69% | 9.8 mph | – |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014739. 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 Boston?
The warmest May temperature on Boston's official record (since 1872) is 97°F, on May 26, 1880; the coldest is 31°F, on May 3, 1882. The wettest May brought 13.38 in (1954).
The May mean against the 1991-2020 normal of 58.4°F: 2021 61.4°F (+3.0), 2022 60.6°F (+2.2), 2023 60.1°F (+1.7), 2024 59.7°F (+1.3), 2025 59.2°F (+0.8), 2026 60.8°F (+2.4). 6 of 6 ran warmer than normal.
| May | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 61.4°F | +3.0°F | 4.92 in |
| 2022 | 60.6°F | +2.2°F | 1.32 in |
| 2023 | 60.1°F | +1.7°F | 2.25 in |
| 2024 | 59.7°F | +1.3°F | 4.82 in |
| 2025 | 59.2°F | +0.8°F | 7.25 in |
| 2026 | 60.8°F | +2.4°F | 2.09 in |
Source: records: ACIS, NWS threaded record BOSthr; recent months: ACIS, station USW00014739. Records and recent months use complete months only.
How does May in Boston compare across Massachusetts?
Across the 35 places PlainClimate covers in Massachusetts, May normal highs run from 61°F in Nantucket to 73°F in Maynard; Boston's is 67°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.