Climate averages 1991–2020
Dorchester weather
in May.
A mild, moderately wet month: the 5th warmest and the 2nd driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
May is a mild month in Dorchester: daytime highs average 18.5°C and nights cool to about 9.5°C. By daytime temperature it is the 5th warmest of the 12 months.
Expect about 81 mm of rain on roughly 11 days, which makes May a moderately wet month (the 2nd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 14 h 34 min on an average May day.
The nearest other city in this atlas is Boston (7 km away). In May its highs average 18.8°C, about as warm as Dorchester, with 81 mm of rain.
Among the 498 cities listed in the United States, Dorchester ranks joint 461st of 498 for the warmest May highs and joint 222nd of 498 for the driest May (rainfall, lowest first). The mean May high of those 498 cities is 23.8°C; Dorchester is 5.3°C cooler than that mean.
From May to June, average highs rise by 5.3°C to 23.8°C, and monthly rainfall rises from 81 mm to 87 mm.
The annual picture
May in context
Monthly precipitation
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Dorchester climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 1.7°C-6.3°C | -6.3°C | 94 | 10.0 | 9.59 h |
| February | 3.0°C-5.5°C | -5.5°C | 84 | 8.9 | 10.511 h |
| March | 6.7°C-1.9°C | -1.9°C | 116 | 11.1 | 11.912 h |
| April | 13.0°C3.8°C | 3.8°C | 100 | 11.0 | 13.313 h |
| May, selected | 18.5°C9.5°C | 9.5°C | 81 | 10.6 | 14.615 h |
| June | 23.8°C15.0°C | 15.0°C | 87 | 10.1 | 15.215 h |
| July | 27.2°C18.6°C | 18.6°C | 73 | 9.6 | 14.915 h |
| August | 26.3°C18.1°C | 18.1°C | 85 | 9.1 | 13.914 h |
| September | 22.2°C14.4°C | 14.4°C | 88 | 8.1 | 12.513 h |
| October | 15.9°C8.5°C | 8.5°C | 108 | 9.8 | 11.111 h |
| November | 9.9°C2.8°C | 2.8°C | 95 | 9.6 | 9.810 h |
| December | 4.6°C-2.4°C | -2.4°C | 115 | 10.8 | 9.29 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
May in nearby cities
- Boston in MayUnited States · 7 kmHigh 18.8°C · Low 9.3°C · 81 mm rain
- Quincy in MayUnited States · 8 kmHigh 18.0°C · Low 9.7°C · 81 mm rain
- Newton in MayUnited States · 12 kmHigh 19.1°C · Low 9.6°C · 77 mm rain
- Lynn in MayUnited States · 21 kmHigh 16.7°C · Low 9.6°C · 84 mm rain
- Brockton in MayUnited States · 24 kmHigh 18.4°C · Low 9.7°C · 77 mm rain
- Lowell in MayUnited States · 42 kmHigh 19.2°C · Low 9.3°C · 78 mm rain
- Lawrence (Massachusetts), United States in MayUnited States · 46 kmHigh 19.2°C · Low 9.4°C · 78 mm rain
- Pawtucket in MayUnited States · 53 kmHigh 19.7°C · Low 10.1°C · 80 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Dorchester) is explained once on the Dorchester year overview and on the Sources, method and limits page.
Boston and Quincy lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.