Boston Weather in May
May in Boston averages 20°C (68°F) during the day and 11°C (52°F) at night. Quite a bit of rainfall is typical this month, with around 100 mm (3.9 in) on average. An umbrella is a good idea.
Rainfall in Boston in May
Expect around 12 days of rain based on historical data, with 100 mm (3.9 in) average. When it rains this month, it tends to come down fairly heavily. Showers can be substantial even if they don't last all day.
Temperature in Boston in May
Expect highs of 20°C (68°F) in Boston in May, with nights dropping to around 11°C (52°F). Temperatures can feel cooler in the morning and evening, so layering is often the best approach. With overnight lows of 11°C (52°F), evenings can feel noticeably cooler than the daytime. An extra layer is a good idea, though the cool air makes for a good night's sleep.
Sunshine in Boston in May
The month enjoys around 301 hours of sunshine, creating mostly sunny days with good weather conditions.
Wind Speed in Boston in May
Average wind conditions reach 6 m/s (12 knots) in May. This creates notably windy weather that is clearly felt and can influence daily activities. Keep in mind this is an average. Some days are less intense, while others can be quite gusty.
Average water temperature in May
The water temperature is only 9°C (48°F) this month — cold enough that most people will want to stay out. Hardy swimmers may manage a quick dip, but it won't be comfortable.For Boston itself, August and September generally stand out with the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our Boston's climate page.
Boston Temperature in May
Min Temperature
11°C (52°F)
Max Temperature
20°C (68°F)
Water Temperature
9°C (48°F)
Chance of Rain
41%
Precipitation
100 mm (3.9 in)
Rainy days
12 days
Humidity
67%
Windspeed
6 m/s (12 knots)
Sunshine
301 hours
Percentage Sunshine
59%
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Boston typically rise from around 17°C (63°F) at the start of May to approximately 22°C (72°F) by the end. Nights are cool, with lows typically ranging from 9°C (48°F) to 14°C (57°F).
Average temperatures in May
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in May
Historical weather for Boston in May
Browse day-by-day weather records for Boston spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Boston historical weather extremes in May
Based on weather observations in Boston between 1976 and 2026, these are the recorded extremes during May.
- The hottest May day on record in Boston reached 36°C (97°F) (May 19, 2026).
- Boston experienced its chilliest May day on May 5, 1987, reaching only 6°C (43°F).
- Nighttime temperatures dropped to 1°C (34°F) on May 10, 2020, marking the coldest May night on record.
Best Places in the United States of America in May
Find out more about the weather in the United States of America and which places have the best travel conditions in this month. See all of the United States of America in May →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in Boston in May
For Boston in May, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. High rain levels are expected, so pack waterproof gear and an umbrella or poncho. Expect water temperatures of around 9°C (48°F), which is definitely too cold for comfortable swimming. Your luggage space is better used for other items. And with plenty of sunshine hours, don’t forget sunglasses, sunscreen, and maybe a sun hat.What To Do in Boston in May
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our Boston's climate page.
Temperature Rainfall Sunshine Humidity Wind Speed Water Temp
See the full Boston climate overview or explore weather in the United States of America.
