South Boston, MA Weather by Month and Climate Averages

How much rain does South Boston get?

South Boston gets 43.6 in of precipitation in an average year, spread over about 128 days with measurable rain. That is more rainy days than 84% of the US.

December is the wettest month, with 4.3 in. February is the driest, with 3.2 in. December has the most rainy days, about 12.

The longest dry spell in the last five years lasted 29 days, to September 18, 2024.

See where South Boston ranks: rainiest cities in the US, US cities with the most rainy days, rainiest cities in Massachusetts.

Does it snow in South Boston?

Yes. South Boston gets about 49.2 in of snow in an average season, measured at the reporting station.

The snowiest winter on record is 2014–15, with 110.6 in.

The most recent measurable snow at the station fell on March 24, 2026.

See where South Boston ranks: snowiest cities in the US.

South Boston weather by month

South Boston weather in January

In January, South Boston averages a high of 37°F and a low of 23°F. It gets 3.4 in of precipitation over about 12 rainy days. The sun is out about 39% of daylight hours. The January record high is 74°F (2020) and the record low is -7°F (2004).

South Boston weather in February

In February, South Boston averages a high of 39°F and a low of 25°F. It gets 3.2 in of precipitation over about 11 rainy days. The sun is out about 42% of daylight hours. The February record high is 73°F (2017) and the record low is -10°F (2023).

South Boston weather in March

In March, South Boston averages a high of 46°F and a low of 31°F. It gets 4.2 in of precipitation over about 12 rainy days. The sun is out about 42% of daylight hours. The March record high is 89°F (1998) and the record low is 5°F (2007).

South Boston weather in April

In April, South Boston averages a high of 57°F and a low of 41°F. It gets 3.6 in of precipitation over about 12 rainy days. The sun is out about 38% of daylight hours. The April record high is 94°F (1976) and the record low is 16°F (1982).

South Boston weather in May

In May, South Boston averages a high of 66°F and a low of 50°F. It gets 3.3 in of precipitation over about 12 rainy days. The sun is out about 42% of daylight hours. The May record high is 96°F (2026) and the record low is 34°F (2020). May is one of the most comfortable months to visit.

South Boston weather in June

In June, South Boston averages a high of 76°F and a low of 60°F. It gets 3.9 in of precipitation over about 11 rainy days. The sun is out about 41% of daylight hours. The June record high is 102°F (2025) and the record low is 45°F (1986). June is one of the most comfortable months to visit.

South Boston weather in July

In July, South Boston averages a high of 82°F and a low of 66°F. It gets 3.3 in of precipitation over about 9 rainy days. The sun is out about 40% of daylight hours. The July record high is 103°F (2011) and the record low is 50°F (1988).

South Boston weather in August

In August, South Boston averages a high of 80°F and a low of 65°F. It gets 3.2 in of precipitation over about 9 rainy days. The sun is out about 41% of daylight hours. The August record high is 102°F (1975) and the record low is 47°F (1986).

South Boston weather in September

In September, South Boston averages a high of 73°F and a low of 58°F. It gets 3.6 in of precipitation over about 9 rainy days. The sun is out about 46% of daylight hours. The September record high is 99°F (1983) and the record low is 38°F (2000). September is one of the most comfortable months to visit.

South Boston weather in October

In October, South Boston averages a high of 62°F and a low of 48°F. It gets 4.0 in of precipitation over about 11 rainy days. The sun is out about 48% of daylight hours. The October record high is 87°F (2011) and the record low is 28°F (1976). October is one of the most comfortable months to visit.

South Boston weather in November

In November, South Boston averages a high of 52°F and a low of 38°F. It gets 3.7 in of precipitation over about 10 rainy days. The sun is out about 59% of daylight hours. The November record high is 82°F (2024) and the record low is 14°F (2018).

South Boston weather in December

In December, South Boston averages a high of 43°F and a low of 29°F. It gets 4.3 in of precipitation over about 12 rainy days. The sun is out about 43% of daylight hours. The December record high is 76°F (1998) and the record low is -7°F (1980).

Sunshine, humidity and wind in South Boston

November is the sunniest month in South Boston, with sunshine about 59% of daylight hours. April is the cloudiest, at 38%. Over the year the sun shines about 43% of daylight hours. South Boston is cloudier than 71% of the US.

Humidity peaks in September at 75% and is lowest in March at 60%.

Wind averages 11 mph over the year, and March is the windiest month at 13 mph.

South Boston has about 14 days a year above 90°F. South Boston is cooler than 70% of the US.

Thunderstorms occur on about 17 days a year.

See where South Boston ranks: sunniest cities in the US, cloudiest cities in the US, hottest cities in the US.

First and last freeze in South Boston

The first fall freeze in South Boston typically comes around November 9, and the last spring freeze around April 6. That leaves a frost-free growing season of about 217 days.

South Boston weather records

The hottest temperature on record at the South Boston station is 103°F, on July 22, 2011. The coldest is -10°F, on February 4, 2023.

The wettest day on record brought 6.1 in of rain, on October 20, 1996.

39 all-time records have been set at the station since 1970.

The annual mean temperature has changed by +0.4°F per decade since 1970.

The best time to visit South Boston

The most comfortable time to visit is typically May to June and September to October, when daytime highs sit near 70°F.

Winter (December–February) is cold, with average highs around 40°F and lows near 26°F. Snow is possible.

Spring (March–May) is mild, with average highs around 56°F and lows near 41°F.

Summer (June–August) is warm, with average highs around 80°F and lows near 64°F. It can feel humid.

Autumn (September–November) is mild, with average highs around 63°F and lows near 48°F.

South Boston climate questions

How much rain does South Boston get?

South Boston gets 43.6 in of precipitation in an average year, over about 128 rainy days.

What is the wettest month in South Boston?

December is the wettest month in South Boston, with 4.3 in. February is the driest, with 3.2 in.

How many rainy days does South Boston have a year?

South Boston has about 128 days with measurable rain in an average year. December has the most, about 12.

Does it snow in South Boston?

Yes. South Boston gets about 49.2 in of snow in an average season. The snowiest winter on record is 2014–15, with 110.6 in.

What is the hottest month in South Boston?

July is the warmest month in South Boston, with an average high of 82°F.

What is the coldest month in South Boston?

January is the coldest month in South Boston, with an average low of 23°F.

What is the record high temperature in South Boston?

The record high at the South Boston station is 103°F, set on July 22, 2011. The record low is -10°F, on February 4, 2023.

What is the sunniest month in South Boston?

November is the sunniest month in South Boston, with sunshine about 59% of daylight hours. April is the cloudiest.

When is the first frost in South Boston?

The first fall freeze in South Boston typically comes around November 9. The last spring freeze is around April 6.

What is the best time to visit South Boston?

The most comfortable time to visit is typically May to June and September to October, when daytime highs sit near 70°F.