Home › Cities › Saint Helena › Jamestown
Jamestown, Saint Helena climate
BSh Hot semi-arid
Jamestown has a remarkably steady warm-temperate climate (Hot semi-arid, Köppen BSh). The hottest month is March with an average daily high near 75°F, while the coldest is August averaging around 58°F at night. Around 17 inches of precipitation falls each year, peaking in June (2.0 inches) and easing off in November (0.7 inches).
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figuresHours of sunshine per day
Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER)Jamestown climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 72 | 74 | 75 | 73 | 71 | 68 | 66 | 64 | 64 | 65 | 67 | 69 |
| Avg temp (°F) | 68 | 70 | 71 | 69 | 67 | 64 | 62 | 61 | 61 | 62 | 63 | 65 |
| Avg low (°F) | 64 | 66 | 67 | 66 | 64 | 61 | 59 | 58 | 58 | 58 | 59 | 61 |
| Precipitation (in) | 1.2 | 1.5 | 1.9 | 1.6 | 1.2 | 2.0 | 1.8 | 1.8 | 1.4 | 1.0 | 0.7 | 0.8 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°F) | 72 | 74 | 75 | 73 | 71 | 68 |
| Avg temp (°F) | 68 | 70 | 71 | 69 | 67 | 64 |
| Avg low (°F) | 64 | 66 | 67 | 66 | 64 | 61 |
| Precipitation (in) | 1.2 | 1.5 | 1.9 | 1.6 | 1.2 | 2.0 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°F) | 66 | 64 | 64 | 65 | 67 | 69 |
| Avg temp (°F) | 62 | 61 | 61 | 62 | 63 | 65 |
| Avg low (°F) | 59 | 58 | 58 | 58 | 59 | 61 |
| Precipitation (in) | 1.8 | 1.8 | 1.4 | 1.0 | 0.7 | 0.8 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 59 | 52 | 54 | 56 | 54 | 62 | 67 | 79 | 82 | 83 | 78 | 70 |
| Relative humidity (%) | 78 | 77 | 77 | 76 | 75 | 73 | 73 | 75 | 78 | 80 | 79 | 78 |
| Wind speed (mph) | 11.8 | 11.9 | 12.4 | 12.6 | 12.3 | 13.1 | 13.5 | 14.1 | 14.0 | 13.9 | 13.2 | 12.2 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 59 | 52 | 54 | 56 | 54 | 62 |
| Relative humidity (%) | 78 | 77 | 77 | 76 | 75 | 73 |
| Wind speed (mph) | 11.8 | 11.9 | 12.4 | 12.6 | 12.3 | 13.1 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 67 | 79 | 82 | 83 | 78 | 70 |
| Relative humidity (%) | 73 | 75 | 78 | 80 | 79 | 78 |
| Wind speed (mph) | 13.5 | 14.1 | 14.0 | 13.9 | 13.2 | 12.2 |
Methodology & sources
Temperature & precipitation — 1991–2020 normals computed from 30 years of daily observations at St. Helena Is., a weather station, about 6 km from the city centre. The underlying daily records come from NOAA's global station network.
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.