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South Portland, Maine climate
Dfb Warm-summer humid continental
South Portland has a strongly seasonal cool-temperate climate (Warm-summer humid continental, Köppen Dfb). The hottest month is July with an average daily high near 80°F, while the coldest is January averaging around 16°F at night. Precipitation is fairly even year-round, totalling about 48 inches. Snowfall is heavy (69 inches 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 countsSouth Portland climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 32 | 35 | 42 | 54 | 64 | 74 | 80 | 79 | 71 | 60 | 48 | 38 |
| Avg temp (°F) | 24 | 26 | 34 | 45 | 55 | 64 | 70 | 69 | 62 | 50 | 40 | 30 |
| Avg low (°F) | 16 | 17 | 26 | 35 | 46 | 55 | 61 | 60 | 52 | 41 | 32 | 22 |
| Precipitation (in) | 3.5 | 3.5 | 4.1 | 4.4 | 3.7 | 4.2 | 3.4 | 3.6 | 3.8 | 5.3 | 4.3 | 4.5 |
| Snowfall (in) | 18.6 | 16.6 | 13.6 | 2.8 | — | — | — | — | — | 0.2 | 2.3 | 14.6 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°F) | 32 | 35 | 42 | 54 | 64 | 74 |
| Avg temp (°F) | 24 | 26 | 34 | 45 | 55 | 64 |
| Avg low (°F) | 16 | 17 | 26 | 35 | 46 | 55 |
| Precipitation (in) | 3.5 | 3.5 | 4.1 | 4.4 | 3.7 | 4.2 |
| Snowfall (in) | 18.6 | 16.6 | 13.6 | 2.8 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°F) | 80 | 79 | 71 | 60 | 48 | 38 |
| Avg temp (°F) | 70 | 69 | 62 | 50 | 40 | 30 |
| Avg low (°F) | 61 | 60 | 52 | 41 | 32 | 22 |
| Precipitation (in) | 3.4 | 3.6 | 3.8 | 5.3 | 4.3 | 4.5 |
| Snowfall (in) | — | — | — | 0.2 | 2.3 | 14.6 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 11 | 10 | 11 | 11 | 12 | 12 | 11 | 9 | 9 | 11 | 11 | 12 |
| Days with high ≥ 90°F (days) | — | — | — | 0.0 | 0.4 | 1 | 2 | 1 | 0.5 | — | — | — |
| Days with low ≤ 32°F (days) | 29 | 26 | 25 | 12 | 0.7 | — | — | — | 0.1 | 6 | 18 | 27 |
| Days with snowfall ≥ 1 in (days) | 5 | 4 | 3 | 0.7 | — | — | — | — | — | 0.1 | 0.7 | 3 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 11 | 10 | 11 | 11 | 12 | 12 |
| Days with high ≥ 90°F (days) | — | — | — | 0.0 | 0.4 | 1 |
| Days with low ≤ 32°F (days) | 29 | 26 | 25 | 12 | 0.7 | — |
| Days with snowfall ≥ 1 in (days) | 5 | 4 | 3 | 0.7 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 11 | 9 | 9 | 11 | 11 | 12 |
| Days with high ≥ 90°F (days) | 2 | 1 | 0.5 | — | — | — |
| Days with low ≤ 32°F (days) | — | — | 0.1 | 6 | 18 | 27 |
| Days with snowfall ≥ 1 in (days) | — | — | — | 0.1 | 0.7 | 3 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 66 | 64 | 63 | 63 | 66 | 64 | 57 | 54 | 54 | 60 | 63 | 64 |
| Clear days (≤ 30% cloud) | 3 | 4 | 6 | 6 | 5 | 5 | 7 | 8 | 9 | 7 | 5 | 5 |
| Partly cloudy days (30–70%) | 12 | 11 | 11 | 10 | 11 | 11 | 13 | 12 | 10 | 10 | 10 | 12 |
| Cloudy days (≥ 70%) | 15 | 13 | 15 | 14 | 16 | 14 | 12 | 11 | 11 | 14 | 14 | 15 |
| Relative humidity (%) | 86 | 84 | 82 | 83 | 86 | 88 | 87 | 85 | 83 | 81 | 80 | 83 |
| Wind speed (mph) | 11.5 | 11.3 | 10.1 | 8.0 | 6.4 | 5.7 | 5.2 | 5.6 | 6.8 | 8.8 | 10.0 | 11.0 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 66 | 64 | 63 | 63 | 66 | 64 |
| Clear days (≤ 30% cloud) | 3 | 4 | 6 | 6 | 5 | 5 |
| Partly cloudy days (30–70%) | 12 | 11 | 11 | 10 | 11 | 11 |
| Cloudy days (≥ 70%) | 15 | 13 | 15 | 14 | 16 | 14 |
| Relative humidity (%) | 86 | 84 | 82 | 83 | 86 | 88 |
| Wind speed (mph) | 11.5 | 11.3 | 10.1 | 8.0 | 6.4 | 5.7 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 57 | 54 | 54 | 60 | 63 | 64 |
| Clear days (≤ 30% cloud) | 7 | 8 | 9 | 7 | 5 | 5 |
| Partly cloudy days (30–70%) | 13 | 12 | 10 | 10 | 10 | 12 |
| Cloudy days (≥ 70%) | 12 | 11 | 11 | 14 | 14 | 15 |
| Relative humidity (%) | 87 | 85 | 83 | 81 | 80 | 83 |
| Wind speed (mph) | 5.2 | 5.6 | 6.8 | 8.8 | 10.0 | 11.0 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Portland Jetport (NOAA GHCN station USW00014764), about 5 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.