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Westford, Massachusetts climate
Cfa Humid subtropical
Westford has a strongly seasonal cool-temperate climate (Humid subtropical, Köppen Cfa). The hottest month is July with an average daily high near 29°C, while the coldest is January averaging around −8°C at night. Precipitation is fairly even year-round, totalling about 1270 mm. Snowfall is heavy (161 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 countsWestford climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 3 | 5 | 9 | 16 | 21 | 26 | 29 | 28 | 24 | 18 | 12 | 6 |
| Avg temp (°C) | −2 | −1 | 3 | 9 | 15 | 20 | 23 | 22 | 18 | 12 | 6 | 1 |
| Avg low (°C) | −8 | −7 | −3 | 3 | 8 | 14 | 17 | 16 | 12 | 6 | 0 | −4 |
| Precipitation (mm) | 98 | 92 | 124 | 110 | 97 | 107 | 102 | 90 | 100 | 121 | 102 | 128 |
| Snowfall (cm) | 44 | 41 | 34 | 6 | — | — | — | — | — | 0 | 4 | 33 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 3 | 5 | 9 | 16 | 21 | 26 |
| Avg temp (°C) | −2 | −1 | 3 | 9 | 15 | 20 |
| Avg low (°C) | −8 | −7 | −3 | 3 | 8 | 14 |
| Precipitation (mm) | 98 | 92 | 124 | 110 | 97 | 107 |
| Snowfall (cm) | 44 | 41 | 34 | 6 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 29 | 28 | 24 | 18 | 12 | 6 |
| Avg temp (°C) | 23 | 22 | 18 | 12 | 6 | 1 |
| Avg low (°C) | 17 | 16 | 12 | 6 | 0 | −4 |
| Precipitation (mm) | 102 | 90 | 100 | 121 | 102 | 128 |
| Snowfall (cm) | — | — | — | 0 | 4 | 33 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 12 | 10 | 13 | 13 | 13 | 12 | 10 | 9 | 9 | 11 | 11 | 12 |
| Days with high ≥ 32°C (days) | — | — | 0.0 | 0.2 | 0.7 | 2 | 5 | 3 | 0.9 | — | — | — |
| Days with low ≤ 0°C (days) | 28 | 25 | 24 | 10 | 0.5 | — | — | — | 0.1 | 4 | 16 | 26 |
| Days with snowfall ≥ 2.5 cm (days) | 4 | 3 | 3 | 0.7 | — | — | — | — | — | 0.2 | 0.4 | 3 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 12 | 10 | 13 | 13 | 13 | 12 |
| Days with high ≥ 32°C (days) | — | — | 0.0 | 0.2 | 0.7 | 2 |
| Days with low ≤ 0°C (days) | 28 | 25 | 24 | 10 | 0.5 | — |
| Days with snowfall ≥ 2.5 cm (days) | 4 | 3 | 3 | 0.7 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 10 | 9 | 9 | 11 | 11 | 12 |
| Days with high ≥ 32°C (days) | 5 | 3 | 0.9 | — | — | — |
| Days with low ≤ 0°C (days) | — | — | 0.1 | 4 | 16 | 26 |
| Days with snowfall ≥ 2.5 cm (days) | — | — | — | 0.2 | 0.4 | 3 |
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 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Reading (NOAA GHCN station USC00196783), about 26 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.