Last updated: January 18, 2025
Saint Thomas Island, part of the U.S. Virgin Islands, exhibits a tropical savanna climate classified as Köppen-Geiger Am. The island experiences a warm average temperature of approximately 26°C (80°F), with seasonal variations that include a minimum of 22°C (72°F) in February and peak maximums reaching 29°C (85°F) in September. This consistent warmth, coupled with its lush landscapes, contributes to the island's vibrant ecosystems and appealing climate for both residents and visitors.
Saint Thomas Island exhibits a distinct warm tropical climate characterized by mild seasonal variations. Throughout the year, temperatures fluctuate slightly, with minimums ranging from 22°C (72°F) in February to 25°C (78°F) in the warmer months of July through September. The average temperature remains consistent, hovering around 25-28°C (77-82°F) across most months, reaching its peak in the summer. Maximum temperatures generally peak at 29°C (84°F) during the summer months of June to October, while the cooler months of January to April see highs mostly between 26-28°C (80-82°F). This stable warmth, coupled with minimal temperature fluctuations, creates an inviting climate year-round, appealing to tourists and supporting the island's lush biodiversity.
Charlotte Amalie experiences a warm climate throughout the year, with February temperatures ranging from a minimum of 22°C (72°F) to a maximum of 29°C (85°F) in September. For more detailed information on the monthly temperatures in Charlotte Amalie, you can visit monthly temperatures in Charlotte Amalie.
Saint Thomas Island experiences a tropical pattern of precipitation, with total rainfall varying significantly throughout the year. The late spring and summer months present the highest rainfall, peaking in September with 161 mm (6.3 in), followed closely by 110 mm (4.3 in) in August. In the cooler months from January to April, precipitation is relatively low, averaging 31-40 mm (1.2-1.6 in) per month. Notably, the frequency of rainy days also increases during the summer, with July and September recording up to 19 days of precipitation, suggesting a shift towards wetter conditions.
As the island transitions from the dry season to a more humid environment, monthly averages reflect this change. The data illustrates a clear increase in rainfall, particularly from May through October, which correlates with the Atlantic hurricane season. December and January generally feature the least amount of rainfall, at 50 mm (2.0 in) and 32 mm (1.3 in), respectively, marking the driest months. This bimodal distribution—characterized by dry winters and wet summers—significantly influences the island's lush vegetation and biodiversity, as well as its appeal to visitors seeking a warm tropical getaway.
Saint Thomas Island enjoys a wealth of sunshine throughout the year, with a clear seasonal trend that illuminates the transition from winter to summer. The year kicks off in January with 258 hours of sunshine, gradually increasing each month. March marks a notable peak, with 349 hours of radiant sunlight, making it one of the sunniest months alongside May, which boasts 358 hours. This consistent rise in sunshine hours characterizes the island's approach to the summer months, creating an inviting atmosphere for residents and tourists alike.
As summer progresses, sunshine remains abundant but begins to stabilize, with hours ranging from 344 to 354 in the following months of June through August. However, the onset of autumn introduces a slight tapering, with September and October receiving around 319 and 316 hours of sunshine, respectively. While these figures still reflect ample sunlight, they signal a gradual return to less sunny conditions as the year closes out, with December offering 320 hours. Overall, the seasonal sunshine patterns showcase Saint Thomas Island as a vibrant locale, bathed in sunlight for most of the year, perfect for outdoor activities and exploration.
The UV Index in Saint Thomas Island reflects the island's intense sun exposure, particularly during the late winter and peak summer months. Starting at a UV Index of 9 in January, the index sharply increases, reaching 11 in February. The summer months of March through June consistently display an extreme UV Index of 13, necessitating caution with only a 10-minute burn time before skin damage can occur. This intensity underscores the importance of sun protection for both residents and visitors as they enjoy outdoor activities.
As the summer progresses, the UV Index reaches its crescendo in September with a remarkable 14, maintaining an extreme level. Post-summer, the UV Index begins to taper off, descending to 12 in October before returning to very high levels of 9 in November and 8 in December. Despite these slight decreases during the winter months, caution is still advised, as both November and December present significant UV risks with burn times of 15 minutes. Overall, the UV Index data highlights the need for sun safety measures year-round in this tropical paradise.
UV Risk Categories
In Saint Thomas Island, daylight duration exhibits a consistent pattern throughout the year, reflective of its tropical setting. Both January and February feature approximately 11 hours of daylight, creating a stable foundation for the winter months. As spring approaches, daylight increases steadily, reaching 12 hours in March and continuing through May. This increase not only enhances outdoor activities but also allows for an extended appreciation of the island's picturesque landscapes during the vibrant spring season.
With the arrival of summer in June and July, daylight peaks at 13 hours, offering ample time for sun-soaked adventures and exploration of the island's natural beauty. As summer wanes, daylight begins to decrease again, returning to 12 hours in August and September before settling back to 11 hours each in October, November, and December. This rhythmic cycle of daylight duration underscores the island's inviting climate, making it an enticing destination for visitors year-round while emphasizing the need for sun safety, particularly during the sunniest months.
Charlotte Amalie in the U.S. Virgin Islands enjoys a tropical climate characterized by warm temperatures year-round. Average temperatures range from 25°C (77°F) in winter to 28°C (82°F) in summer, with highs peaking at 29°C (84-85°F) in mid-year months. Precipitation fluctuates throughout the year, with the wettest months being September (161 mm) and August (110 mm), and the driest in February (31 mm) and January (32 mm). Sunshine is abundant, particularly in March, April, and May, boasting over 349 hours per month. For more details, visit Charlotte Amalie climate.
In conclusion, Saint Thomas Island presents a captivating climate characterized by warm temperatures, abundant sunshine, and significant UV exposure throughout the year. The tropical savanna climate fosters a vibrant environment, with seasonal patterns showcasing a transition from cooler, drier months to a hot and humid summer filled with sunshine and increased rainfall. The notable variations in precipitation and daylight duration further enrich the island's ecosystem, enhancing its allure for tourists seeking both relaxation and adventure. As visitors indulge in the island's natural wonders, it remains crucial to prioritize sun safety due to the intense UV Index, ensuring a healthy and enjoyable experience on this tropical paradise.