Climate Chart of Jamestown, Saint Helena, Ascension and Tristan da Cunha
Monthly data: Temperature °C, Rain (mm), Sunshine (h) · 2013–2023
For Jamestown, Saint Helena, Ascension and Tristan da Cunha, the climate data cover 2013–2023. The monthly mean temperature averages 21.1 °C, with the highest monthly mean in March at 23.6 °C and the lowest in September at 18.9 °C. Mean daily rainfall averages 0.49 mm/day, while mean daily sunshine averages 10.60 hours/day. Together, these figures sketch a year with modest monthly temperature variation, low average daily rainfall, and substantial daily sunshine, while leaving day-to-day conditions unspecified.
Climate overview
Temperature
Monthly mean temperatures reach their highest point in March, at 23.6 °C, and their lowest in September, at 18.9 °C. These are averages for each month, not daytime maximum temperatures, so they describe the broad temperature baseline rather than the full range a visitor may experience during a day. Across the calendar-month means, the unweighted mean is 21.1 °C; it is not a day-weighted annual average.
Rain
Mean daily rainfall is highest in July, at 0.61 mm/day, and lowest in November, at 0.36 mm/day. The unweighted mean across calendar-month means is 0.49 mm/day. These are average daily amounts, not monthly totals; the lower monthly mean does not guarantee dry days or indicate how frequently rain occurs.
Sunshine
Mean daily sunshine duration is highest in January, at 11.76 hours/day, and lowest in August, at 9.62 hours/day. The unweighted mean across calendar-month means is 10.60 hours/day. These figures can help with broad outdoor-planning expectations, but sunshine duration is not day length and monthly averages do not promise the conditions on a particular day.
Best Travel Time Guide for Jamestown, Saint Helena, Ascension and Tristan da Cunha: Ideal Seasons and Weather Insights
For visitors prioritising lower average rainfall, November is the conditional option indicated by the lowest mean daily rainfall, 0.36 mm/day; this does not guarantee rain-free days or measure rain frequency. Rain preparation is especially relevant in July, when mean daily rainfall reaches 0.61 mm/day. Those seeking cooler monthly mean temperatures can consider September, the coolest month by this measure at 18.9 °C. For outdoor planning around sunshine, the mean daily duration is highest in January at 11.76 hours/day, and lowest in August at 9.62 hours/day. These are separate criteria rather than a single best-time ranking, and averages cannot predict any particular day's weather.
Climate Data Overview for Jamestown, Saint Helena, Ascension and Tristan da Cunha
Explore the comprehensive climate data for Jamestown, Saint Helena, Ascension and Tristan da Cunha. This detailed table provides valuable insights into temperature variations, precipitation levels, and seasonal changes, helping you understand the unique weather patterns of this region.
| Month | Average: Temperature °C | Rain (mm) / day | Snow (mm) / day | Sunshine (h) / day |
|---|---|---|---|---|
| Jan | 22.2 | 0.46 | 0.00 | 11.76 |
| Feb | 23.3 | 0.44 | 0.00 | 11.45 |
| Mar | 23.6 | 0.60 | 0.00 | 10.93 |
| Apr | 23.2 | 0.48 | 0.00 | 10.63 |
| May | 22.3 | 0.47 | 0.00 | 10.24 |
| Jun | 21.0 | 0.58 | 0.00 | 9.78 |
| Jul | 19.9 | 0.61 | 0.00 | 9.68 |
| Aug | 19.2 | 0.51 | 0.00 | 9.62 |
| Sep | 18.9 | 0.48 | 0.00 | 9.99 |
| Oct | 19.0 | 0.39 | 0.00 | 10.29 |
| Nov | 19.7 | 0.36 | 0.00 | 11.14 |
| Dec | 20.8 | 0.51 | 0.00 | 11.65 |
| Average | 21.1 | 0.49 | 0.00 | 10.60 |
