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Boston, Massachusetts climate
Cfa Humid subtropical
Boston has a seasonal cool-temperate climate (Humid subtropical, Köppen Cfa). The hottest month is July with an average daily high near 28°C, while the coldest is January averaging around −5°C at night. Precipitation is fairly even year-round, totalling about 1107 mm. Winters bring significant snowfall (125 cm of snow per year on average).
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation split into rain and snow · 1991–2020 normals · hover a month for the exact figuresClear vs cloudy days
Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day countsBoston climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 3 | 4 | 8 | 14 | 19 | 25 | 28 | 27 | 23 | 17 | 11 | 6 |
| Avg temp (°C) | −1 | 0 | 4 | 9 | 15 | 20 | 23 | 23 | 19 | 13 | 7 | 2 |
| Avg low (°C) | −5 | −4 | −1 | 5 | 10 | 15 | 19 | 18 | 15 | 9 | 3 | −2 |
| Precipitation (mm) | 86 | 82 | 106 | 92 | 83 | 99 | 83 | 82 | 90 | 102 | 93 | 109 |
| Snowfall (cm) | 36 | 37 | 23 | 4 | — | — | — | — | — | 1 | 2 | 23 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 3 | 4 | 8 | 14 | 19 | 25 |
| Avg temp (°C) | −1 | 0 | 4 | 9 | 15 | 20 |
| Avg low (°C) | −5 | −4 | −1 | 5 | 10 | 15 |
| Precipitation (mm) | 86 | 82 | 106 | 92 | 83 | 99 |
| Snowfall (cm) | 36 | 37 | 23 | 4 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 28 | 27 | 23 | 17 | 11 | 6 |
| Avg temp (°C) | 23 | 23 | 19 | 13 | 7 | 2 |
| Avg low (°C) | 19 | 18 | 15 | 9 | 3 | −2 |
| Precipitation (mm) | 83 | 82 | 90 | 102 | 93 | 109 |
| Snowfall (cm) | — | — | — | 1 | 2 | 23 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 12 | 11 | 12 | 12 | 12 | 11 | 9 | 9 | 9 | 10 | 10 | 12 |
| Days with high ≥ 32°C (days) | — | — | — | 0.1 | 0.6 | 3 | 6 | 4 | 0.8 | — | — | — |
| Days with low ≤ 0°C (days) | 25 | 22 | 16 | 2 | — | — | — | — | — | 0.2 | 7 | 20 |
| Days with snowfall ≥ 2.5 cm (days) | 4 | 3 | 2 | 0.3 | — | — | — | — | — | 0.1 | 0.2 | 2 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 12 | 11 | 12 | 12 | 12 | 11 |
| Days with high ≥ 32°C (days) | — | — | — | 0.1 | 0.6 | 3 |
| Days with low ≤ 0°C (days) | 25 | 22 | 16 | 2 | — | — |
| Days with snowfall ≥ 2.5 cm (days) | 4 | 3 | 2 | 0.3 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 9 | 9 | 9 | 10 | 10 | 12 |
| Days with high ≥ 32°C (days) | 6 | 4 | 0.8 | — | — | — |
| Days with low ≤ 0°C (days) | — | — | — | 0.2 | 7 | 20 |
| Days with snowfall ≥ 2.5 cm (days) | — | — | — | 0.1 | 0.2 | 2 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 63 | 62 | 62 | 64 | 65 | 63 | 57 | 56 | 55 | 60 | 62 | 63 |
| Clear days (≤ 30% cloud) | 5 | 5 | 6 | 5 | 5 | 5 | 6 | 7 | 9 | 7 | 6 | 5 |
| Partly cloudy days (30–70%) | 11 | 11 | 10 | 10 | 10 | 11 | 14 | 12 | 10 | 10 | 10 | 12 |
| Cloudy days (≥ 70%) | 14 | 13 | 14 | 15 | 16 | 14 | 11 | 12 | 11 | 14 | 14 | 14 |
| Relative humidity (%) | 88 | 87 | 83 | 80 | 79 | 79 | 74 | 73 | 74 | 78 | 82 | 86 |
| Wind speed (km/h) | 3.7 | 4.2 | 3.7 | 2.3 | 1.6 | 1.4 | 1.3 | 1.4 | 1.7 | 2.2 | 2.4 | 2.8 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 63 | 62 | 62 | 64 | 65 | 63 |
| Clear days (≤ 30% cloud) | 5 | 5 | 6 | 5 | 5 | 5 |
| Partly cloudy days (30–70%) | 11 | 11 | 10 | 10 | 10 | 11 |
| Cloudy days (≥ 70%) | 14 | 13 | 14 | 15 | 16 | 14 |
| Relative humidity (%) | 88 | 87 | 83 | 80 | 79 | 79 |
| Wind speed (km/h) | 3.7 | 4.2 | 3.7 | 2.3 | 1.6 | 1.4 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 57 | 56 | 55 | 60 | 62 | 63 |
| Clear days (≤ 30% cloud) | 6 | 7 | 9 | 7 | 6 | 5 |
| Partly cloudy days (30–70%) | 14 | 12 | 10 | 10 | 10 | 12 |
| Cloudy days (≥ 70%) | 11 | 12 | 11 | 14 | 14 | 14 |
| Relative humidity (%) | 74 | 73 | 74 | 78 | 82 | 86 |
| Wind speed (km/h) | 1.3 | 1.4 | 1.7 | 2.2 | 2.4 | 2.8 |
30-year delta table (1991–2020 minus 1981–2010, °F)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Δ Max temp | +1.0 | +0.3 | +0.1 | +0.8 | +0.5 | +0.3 | +0.7 | +0.8 | +0.7 | +0.7 | +0.1 | +1.0 |
| Δ Avg temp | +0.9 | +0.1 | +0.0 | +0.5 | +0.5 | +0.3 | +0.7 | +0.6 | +0.7 | +0.8 | +0.0 | +1.0 |
| Δ Min temp | +0.9 | -0.1 | +0.0 | +0.2 | +0.4 | +0.2 | +0.6 | +0.5 | +0.8 | +1.0 | -0.1 | +1.0 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Δ Max temp | +1.0 | +0.3 | +0.1 | +0.8 | +0.5 | +0.3 |
| Δ Avg temp | +0.9 | +0.1 | +0.0 | +0.5 | +0.5 | +0.3 |
| Δ Min temp | +0.9 | -0.1 | +0.0 | +0.2 | +0.4 | +0.2 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Δ Max temp | +0.7 | +0.8 | +0.7 | +0.7 | +0.1 | +1.0 |
| Δ Avg temp | +0.7 | +0.6 | +0.7 | +0.8 | +0.0 | +1.0 |
| Δ Min temp | +0.6 | +0.5 | +0.8 | +1.0 | -0.1 | +1.0 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Boston (NOAA GHCN station USW00014739), about 4 km from the city centre.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.