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Sumter, South Carolina climate
Cfa Humid subtropical
Sumter has a seasonal mild-temperate climate (Humid subtropical, Köppen Cfa). The hottest month is July with an average daily high near 32°C, while the coldest is January averaging around 0°C at night. Precipitation is fairly even year-round, totalling about 1240 mm.
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 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 countsSumter climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 13 | 15 | 19 | 24 | 27 | 31 | 32 | 31 | 29 | 24 | 18 | 14 |
| Avg temp (°C) | 7 | 8 | 12 | 17 | 21 | 25 | 27 | 26 | 23 | 17 | 11 | 8 |
| Avg low (°C) | 0 | 2 | 5 | 10 | 14 | 19 | 21 | 20 | 17 | 11 | 4 | 2 |
| Precipitation (mm) | 96 | 88 | 93 | 86 | 96 | 128 | 146 | 125 | 111 | 99 | 75 | 97 |
| Snowfall (cm) | 1 | — | — | — | — | — | — | — | — | — | — | — |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 13 | 15 | 19 | 24 | 27 | 31 |
| Avg temp (°C) | 7 | 8 | 12 | 17 | 21 | 25 |
| Avg low (°C) | 0 | 2 | 5 | 10 | 14 | 19 |
| Precipitation (mm) | 96 | 88 | 93 | 86 | 96 | 128 |
| Snowfall (cm) | 1 | — | — | — | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 32 | 31 | 29 | 24 | 18 | 14 |
| Avg temp (°C) | 27 | 26 | 23 | 17 | 11 | 8 |
| Avg low (°C) | 21 | 20 | 17 | 11 | 4 | 2 |
| Precipitation (mm) | 146 | 125 | 111 | 99 | 75 | 97 |
| Snowfall (cm) | — | — | — | — | — | — |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 11 | 9 | 9 | 8 | 9 | 12 | 11 | 11 | 9 | 8 | 8 | 11 |
| Days with high ≥ 32°C (days) | — | — | — | 0.5 | 4 | 12 | 19 | 14 | 6 | 0.3 | — | — |
| Days with low ≤ 0°C (days) | 16 | 11 | 7 | 0.4 | — | — | — | — | — | 0.4 | 6 | 14 |
| Days with snowfall ≥ 2.5 cm (days) | 0.1 | — | — | — | — | — | — | — | — | — | — | — |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 11 | 9 | 9 | 8 | 9 | 12 |
| Days with high ≥ 32°C (days) | — | — | — | 0.5 | 4 | 12 |
| Days with low ≤ 0°C (days) | 16 | 11 | 7 | 0.4 | — | — |
| Days with snowfall ≥ 2.5 cm (days) | 0.1 | — | — | — | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 11 | 11 | 9 | 8 | 8 | 11 |
| Days with high ≥ 32°C (days) | 19 | 14 | 6 | 0.3 | — | — |
| Days with low ≤ 0°C (days) | — | — | — | 0.4 | 6 | 14 |
| Days with snowfall ≥ 2.5 cm (days) | — | — | — | — | — | — |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 56 | 59 | 54 | 51 | 52 | 56 | 56 | 57 | 51 | 44 | 47 | 55 |
| Clear days (≤ 30% cloud) | 9 | 7 | 9 | 10 | 9 | 7 | 6 | 6 | 10 | 14 | 12 | 9 |
| Partly cloudy days (30–70%) | 10 | 9 | 10 | 10 | 11 | 12 | 14 | 13 | 11 | 8 | 9 | 9 |
| Cloudy days (≥ 70%) | 13 | 12 | 12 | 10 | 11 | 11 | 11 | 12 | 10 | 10 | 9 | 12 |
| Relative humidity (%) | 81 | 81 | 79 | 75 | 70 | 70 | 69 | 71 | 72 | 72 | 73 | 79 |
| Wind speed (km/h) | 8.6 | 9.0 | 9.5 | 9.5 | 8.4 | 7.5 | 7.2 | 6.8 | 7.8 | 7.8 | 7.8 | 8.0 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 56 | 59 | 54 | 51 | 52 | 56 |
| Clear days (≤ 30% cloud) | 9 | 7 | 9 | 10 | 9 | 7 |
| Partly cloudy days (30–70%) | 10 | 9 | 10 | 10 | 11 | 12 |
| Cloudy days (≥ 70%) | 13 | 12 | 12 | 10 | 11 | 11 |
| Relative humidity (%) | 81 | 81 | 79 | 75 | 70 | 70 |
| Wind speed (km/h) | 8.6 | 9.0 | 9.5 | 9.5 | 8.4 | 7.5 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 56 | 57 | 51 | 44 | 47 | 55 |
| Clear days (≤ 30% cloud) | 6 | 6 | 10 | 14 | 12 | 9 |
| Partly cloudy days (30–70%) | 14 | 13 | 11 | 8 | 9 | 9 |
| Cloudy days (≥ 70%) | 11 | 12 | 10 | 10 | 9 | 12 |
| Relative humidity (%) | 69 | 71 | 72 | 72 | 73 | 79 |
| Wind speed (km/h) | 7.2 | 6.8 | 7.8 | 7.8 | 7.8 | 8.0 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Sumter (NOAA GHCN station USC00388440), about 2 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.