Last updated: January 18, 2025
The climate of Ascension, part of Saint Helena, Ascension, and Tristan da Cunha, is classified under the Köppen-Geiger system as Am, indicating a tropical monsoon climate. Characterized by consistently warm temperatures, the region experiences a minimum of 22°C (72°F) in October, while the annual average hovers around 25°C (77°F). The warmest temperatures are recorded in March, reaching a maximum of 28°C (83°F). This tropical environment not only influences the local biodiversity but also shapes the unique ecological characteristics of the island.
Temperature patterns in Ascension, Saint Helena, Ascension and Tristan da Cunha exhibit a tropical warmth throughout the year with subtle seasonal variations. The warmest months are from January to April, where temperatures consistently range from a minimum of 23°C (74°F) to a maximum of 28°C (83°F), peaking in March and April. As the year progresses into the cooler months from May to August, there is a gradual decline in average temperatures, dipping to 24°C (75°F) and lower. August marks the coolest period, with minimums reaching 22°C (72°F). From September to December, temperatures begin to rise again, though they remain stable, fluctuating only slightly between 22°C (72°F) and 26°C (79°F). This pattern illustrates a distinct tropical climate, marked by a warm, stable environment with a gentle seasonal shift toward cooler months.
Georgetown experiences moderate temperatures throughout the year, with a minimum of 22°C (72°F) in October and a maximum reaching 28°C (83°F) in March. This consistent climate makes it an appealing destination for visitors year-round. For more detailed insights, you can explore the monthly temperatures in Georgetown.
Precipitation in Ascension, part of Saint Helena, Ascension, and Tristan da Cunha, demonstrates a distinct seasonal pattern, with the wettest months generally occurring from March to April. Rainfall begins modestly in January with only 9 mm (0.3 in) and gradually increases, peaking at 21 mm (0.8 in) in April. This increase is accompanied by a rise in rainy days, starting from just 1 day in January to 7 days in April, suggesting a transition into a more humid climate as the region approaches mid-year.
Following April, average precipitation decreases slightly, with May and June experiencing 14 mm (0.6 in) each. July and August see a slight uptick to 17 mm (0.7 in) and 19 mm (0.8 in), respectively. Interestingly, the latter months of the year, from September to December, witness a decline in both rainfall and rainy days, culminating in November, where 11 mm (0.4 in) is recorded over just 0 days of rain. Overall, this pattern reflects a predominantly dry climate with concentrated wet periods, characteristic of tropical environments.
The sunshine duration in Ascension, part of Saint Helena, Ascension, and Tristan da Cunha, exhibits a clear seasonal trend with peaks during the summer months. January starts the year with a robust 282 hours of sunlight, but this figure steadily rises, reaching its zenith in March at 340 hours. This increase is indicative of the transitioning weather patterns as the island moves into summer. Following March, the sun continues to shine brightly, albeit slightly diminished, with 323 hours in April and maintaining 323 hours in May, illustrating a sustained period of ample sunshine that characterizes the summer season.
As the year progresses into the cooler months, the total sunshine hours begin to fluctuate but remain relatively high. From June to August, hours hover around 302 to 313 hours, proving that even in winter, Ascension enjoys a considerable amount of sunlight, avoiding the drastic reductions seen in many temperate regions. Interestingly, September shows a dip to 283 hours, followed by a recovery as the island welcomes back brighter days in the later months, culminating in 319 hours of sunshine in December. Overall, the year is marked by vibrant sunshine during the warmer months, with a notable resilience in brightness even through the winter period.
The UV Index in Ascension, part of Saint Helena, Ascension, and Tristan da Cunha, reflects a notable consistency in the extreme levels of solar radiation, particularly during the summer months. From January to March, the UV Index reaches a peak of 14, categorized as extreme, indicating that unprotected skin can burn in just 10 minutes. As temperatures warm up, such consistent exposure underscores the importance of sun safety measures for both residents and visitors. April sees a slight decline to 13, but the extreme exposure persists, demonstrating that even during the transitional months, vigilance is crucial to prevent sunburn.
As the region moves into winter, the UV Index remains relatively high, although it does experience a gentle decline. In June and July, the Index drops to 10, categorized as very high, with burn time extending to 15 minutes. By late winter and early spring, conditions shift again with the UV Index rising back to 12 in September and 14 in November and December. This pattern highlights a year-round need for sun protection, especially given that extreme levels are prevalent for a significant portion of the year, reinforcing the responsibility of outdoor enthusiasts to remain aware of these indices while enjoying the island's sunny climate.
UV Risk Categories
Daylight duration in Ascension, part of Saint Helena, Ascension, and Tristan da Cunha, showcases a stable and consistent pattern throughout the year, particularly notable in the summer months. From January through March, residents enjoy a generous 12 hours of daylight each day, which supports an active outdoor lifestyle. As the island transitions into late spring and early summer, daylight duration decreases slightly to 11 hours between April and August. This period marks the island’s winter, yet the difference is minimal, reflecting the relatively stable equatorial climate of the region.
As the year progresses into fall and winter, daylight duration begins to recover, returning to 12 hours from September onward. By the end of the calendar year, both November and December maintain this generous daylight length, ensuring that the island remains bright and vibrant for its inhabitants and visitors. Overall, Ascension experiences a unique blend of stability and predictability in daylight hours, with minimal fluctuations across seasons, allowing for an abundance of opportunities for outdoor activities throughout the year.
Georgetown, located in Saint Helena, Ascension, and Tristan da Cunha, enjoys a mild climate throughout the year, with average temperatures ranging from 24°C (75°F) to 27°C (81°F). The warmest months are March and April, while the coolest occur in July and August. Precipitation is relatively low, peaking in April at 21 mm (0.8 in) and remaining below 20 mm for most of the year. Residents can expect plenty of sunshine, particularly in March, which boasts up to 340 hours of sunlight. For more information, visit Georgetown climate.
In conclusion, the climate and environmental conditions of Ascension, part of Saint Helena, Ascension, and Tristan da Cunha, present a captivating mix of tropical warmth, ample sunshine, and high UV levels throughout the year. The consistent temperature patterns, characterized by minimal seasonal fluctuation, combined with a stable daylight duration, offer residents and visitors a pleasant environment for outdoor pursuits. However, the extreme UV Index during the summer months underscores the necessity for sun protection to enjoy the island safely. Overall, Ascension’s climate not only supports a rich array of biodiversity but also fosters a vibrant lifestyle, inviting exploration and appreciation of its unique natural beauty.