| Average climate data for Tristan da Cunha, Saint Helena, Ascension and Tristan da Cunha | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average maximum temperature (°C) | 20 | 21 | 20 | 18 | 17 | 15 | 14 | 14 | 14 | 15 | 17 | 19 | 21 |
| Average minimum temperature (°C) | 16 | 17 | 16 | 15 | 13 | 11 | 11 | 10 | 10 | 11 | 13 | 15 | 10 |
| Average precipitation (mm) | 94 | 113 | 120 | 131 | 157 | 160 | 160 | 173 | 169 | 149 | 129 | 126 | 1,680 |
| Average rainfall days (days) | 18 | 16 | 17 | 20 | 23 | 23 | 25 | 26 | 24 | 22 | 18 | 19 | 251 |
| Average water temperature (°C) | 17 | 18 | 18 | 17 | 16 | 15 | 14 | 13 | 13 | 14 | 15 | 16 | 16 |
| Average daily daylight hours (h) | 14 | 13 | 12 | 11 | 10 | 9 | 9 | 10 | 11 | 13 | 14 | 14 | 12 |
| Average daily sunshine hours (h) | 4 | 5 | 4 | 4 | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 4 |
| Average UV index | 12 | 10 | 8 | 5 | 3 | 2 | 2 | 3 | 5 | 7 | 10 | 11 | 6 |
The warmest month, with the highest average maximum temperature, is February (20.9 °C). The month with the lowest average maximum temperature is July (14 °C). Overall, the average maximum temperature over the whole year is 17 °C.
The month with the highest average minimum temperature is February (17.1 °C). The coldest month, with the lowest average minimum temperature, is August (9.9 °C). Overall, the average minimum temperature over the whole year is 13.2 °C.
The month with the highest average water temperature is February (18 °C). The month with the lowest average water temperature is September (13 °C). Overall, the average water temperature over the whole year is 15.5 °C.
The wettest month, with the highest amount of precipitation, is August (173.4 mm). The driest month, with the least amount of precipitation, is January (93.7 mm). Over the whole year there are 1,680 mm of rainfall on average.
The month with the most days of rain is August (25.9 days). The month with the fewest days of rain is February (16 days). Over the whole year there are 251 days of rain on average.
The month with the longest days, so the most daylight, is December (Average daylight: 14.1 h). The month with the shortest days, so the least daylight, is June (Average daylight: 9.1 h). Over the whole year there are 11.7 h of daylight per day on average.
The month with the most sunshine per day is February (Average sunshine: 5.1 h). The month with the least sunshine per day is August (Average sunshine: 2.9 h). Over the whole year there are 3.8 h of sunlight per day on average.
The month with the highest average UV index is January (UV index: 12). The months with the lowest average UV index are June and July (UV index: 2). Over the whole year the average UV index is 6.5.
