Last updated: October 31, 2025
September in Gustavia, Saint Barthélemy, offers warm and tropical conditions, with average temperatures hovering around 28°C (82°F). Maximum highs can reach 29°C (85°F), while the nights remain pleasant at a minimum of 25°C (77°F). However, this month also experiences considerable precipitation, with a total of 152 mm (6.0 in) spread over 22 days, resulting in a humidity level of 80%. Visitors should be prepared for the lush and vibrant ambiance that September brings, characterized by occasional rain showers interspersed with sunny moments, making it a unique time to enjoy the beauty of this stunning Caribbean destination.
In September, Gustavia, Saint Barthélemy, continues to bask in the warmth of the Caribbean, showcasing temperatures that reflect a delightful late summer vibe. The month marks a steady progression in warmth, with minimums hovering around 25°C (77°F) and averages reaching 28°C (82°F). As the maximum temperatures peak at 29°C (85°F), it’s clear that September is one of the hotter months, perfectly suited for sun-soaked beach days and vibrant sunset views. This warmth mirrors the rising trend seen throughout the summer, inviting visitors to enjoy leisurely afternoons in the sun before the cooler autumn air begins to set in.
September in Gustavia, Saint Barthélemy, marks a significant uptick in precipitation, with the island receiving a substantial 152 mm (6.0 in) of rain over 22 days. This sharp contrast to earlier months, where rainfall remained below 100 mm, highlights September as one of the wettest months of the year. The increase not only underscores the transition into the rainy season but also reflects a broader climatic trend towards higher moisture levels, particularly when compared to the preceding months of July and August, which averaged around 80 mm and 86 mm respectively. As summer gives way to fall, visitors should be prepared for the unpredictable showers that contribute to the island's lush greenery and vibrant ecosystem.
In September, humidity in Gustavia, Saint Barthélemy continues to reflect the island's warm tropical climate, averaging around 80%. This slight dip from the peak summer months of July and August, which saw humidity levels at 83% and 82% respectively, indicates a gradual transition toward the cooler and drier months ahead. As the year progresses, humidity remains relatively consistent, fluctuating only a few percentage points from January through June. This pattern underscores the gradual shift in weather as the island approaches autumn, allowing visitors to experience slightly more comfortable conditions while still enjoying the lush, vibrant ecosystems that thrive in such humid environments.
In September, Gustavia, Saint Barthélemy, experiences an UV Index of 13, placing it firmly within the extreme exposure category. This trend reflects the conditions seen throughout the summer months, where the UV Index consistently hovers at the same high level. With a burn time of just 10 minutes, it's crucial for sunbathers and outdoor enthusiasts to prioritize sun protection. This extreme index is not uncommon in the preceding months of June, July, and August, hinting at a prolonged season of strong sun exposure. As autumn approaches in October, there is a slight decrease to an index of 12, still categorized as extreme. For detailed insights on how to safeguard against UV exposure, explore more at Gustavia UV Index.
UV Risk Categories
As September rolls into Gustavia, Saint Barthélemy, the island basks in 323 hours of glorious sunshine, marking a smooth transition from the vibrant summer months. This month reflects a slight dip from the sun-drenched July peak of 364 hours but remains comfortably above the early months of the year. The progression of daylight hours showcases a consistent warmth, with May and June leading the way as the sunniest months, while September continues to offer a cozy embrace of sunshine, beckoning visitors to enjoy its breathtaking beaches and lively atmosphere. With just a whisper of autumn in the air, September’s golden rays ensure that Gustavia remains a sun-soaked paradise, perfect for relaxation and adventure alike.
In Gustavia, Saint Barthélemy, September boasts a 58% chance of sunny weather, making it one of the more promising months for those seeking sunshine. While this figure is slightly higher than the drier summer months of June (25%) and August (47%), it still falls short compared to the more favorable conditions seen earlier in the year, particularly in February and March, when the likelihood of clear skies peaks at 71% and 72%, respectively. Overall, September marks a transitional period as the island begins to shift from the rainy season, offering visitors a decent opportunity to bask in the sun while enjoying the breathtaking Caribbean views.
In Gustavia, Saint Barthélemy, September enjoys a delightful 12 hours of daylight, a continuation of the sun-kissed warmth that prevails throughout the summer months. As the year progresses from the consistent 11 hours in January and February to the peak of 13 hours seen in June and July, the daylight gradually begins to taper off, transitioning back to 11 hours by October. This gentle decrease highlights the island's tropical charm, where day and night balance gracefully, allowing visitors to bask in the radiant sunshine while preparing for the picturesque, slightly shorter days that autumn brings. The rhythm of daylight in Gustavia creates a seamless blend of vibrant activities and serene moments, making every September day a chance to embrace the beauty of the Caribbean.
As September arrives in Gustavia, Saint Barthélemy, the winds begin to soften, with an average speed dipping to 5.3 m/s (12 mph)—the calmest of the year. This gentle breeze marks a transition from the lively summer months, where winds peaked at 8.4 m/s (19 mph) in July and remained robust through August. The decline in wind speed suggests a cozy atmosphere perfect for savoring the island's serene beauty and relaxed vibe. As the calendar turns towards October, the winds gradually pick up again, hinting at an approaching change while still providing a tranquil escape during this early autumn month.
Weather in Gustavia varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Gustavia, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January weather exhibits notable differences, particularly in temperature and precipitation. September sees warmer conditions with an average temperature of 28°C (82°F) and higher humidity at 80%. It's also marked by significant rainfall, accumulating 152 mm (6.0 in) over 22 days. In contrast, January offers a gentler climate, with temperatures averaging around 25°C (78°F) and a reduced humidity level of 77%. Additionally, it experiences much lower precipitation at only 35 mm (1.4 in) over 13 days. For more details about January weather in Gustavia, you can check this link: Gustavia weather in January.
In comparing the weather between September and February, we see a notable difference in temperature and precipitation patterns. September experiences warmer temperatures, with a minimum of 25°C (77°F) and an average of 28°C (82°F), contrasted with February's cooler minimum of 22°C (72°F) and an average of 25°C (77°F). Additionally, September is significantly wetter, receiving 152 mm (6.0 in) of rain over 22 days, while February only sees 35 mm (1.4 in) of rainfall across 11 days. Humidity levels are similar, with September slightly higher at 80% compared to February's 77%. For more details on weather conditions, visit Gustavia weather in February.
In comparing the weather between September and March, September boasts warmer temperatures with a minimum of 25°C (77°F) and an average of 28°C (82°F), while March presents slightly cooler conditions with a minimum of 22°C (73°F) and an average of 25°C (77°F). Additionally, September experiences significantly higher precipitation, with 152 mm (6.0 in) spread over 22 days, compared to March's much lighter rainfall of 27 mm (1.1 in) on just 10 days. Humidity levels are relatively close, with September at 80% and March at 77%. For more detailed information about March weather, visit Gustavia weather in March.
Comparing the weather of September and April, we can see some notable differences. September typically experiences warmer temperatures, with averages around 28°C (82°F) and highs reaching up to 29°C (85°F), while April has a cooler average of 25°C (78°F) and a maximum of 27°C (81°F). Additionally, September is much wetter, receiving 152 mm (6.0 in) of precipitation over 22 days, compared to April's lighter rainfall of 34 mm (1.3 in) across just 11 days. Humidity levels are relatively similar, with September at 80% and April slightly lower at 78%. For more detailed insights, check out the Gustavia weather in April.
In comparing the weather of September and May, September tends to be warmer with a minimum temperature of 25°C (77°F) and an average of 28°C (82°F), while May features slightly cooler temperatures with a minimum of 23°C (74°F) and an average of 26°C (79°F). September also sees significantly higher precipitation, with 152 mm (6.0 in) over 22 days compared to May's 47 mm (1.8 in) across just 12 days. Humidity levels remain quite similar in both months, with September at 80% and May at 79%. For a closer look at how the weather differs, you can check out Gustavia weather in May.
In comparing the weather of September and June, we can see some notable differences. September boasts slightly higher average temperatures, with a minimum of 25°C (77°F), an average of 28°C (82°F), and a maximum of 29°C (85°F). However, it also experiences considerably more precipitation, totaling 152 mm (6.0 in) over 22 days, and higher humidity at 80%. In contrast, June features a minimum of 25°C (76°F), an average of 27°C (81°F), and a maximum of 28°C (84°F), with much lower precipitation of 49 mm (1.9 in) across 14 days, and a humidity level of 81%. For more specific details about June weather, you can visit Gustavia weather in June.
In comparing the weather between September and July, we see that both months have similar temperature ranges, with September averaging slightly warmer at 28°C (82°F) versus July's 27°C (81°F). However, September experiences significantly more rainfall, with 152 mm (6.0 in) on 22 days, compared to July's 80 mm (3.2 in) over 17 days. Humidity levels are also higher in September at 80%, whereas July averages around 83%. For more details on July weather, you can visit Gustavia weather in July.
In comparing the weather between August and September, we find that both months maintain similar temperature patterns, with minimums at 25°C (77°F), average temperatures around 28°C (82°F), and maximums reaching 29°C (84°F in August and 85°F in September). However, September is notably wetter, receiving 152 mm (6.0 in) of precipitation over 22 days, compared to August's 86 mm (3.4 in) over just 16 days. Humidity remains high in both months, with September slightly lower at 80% compared to August's 82%. For more detailed information on weather patterns in August, you can visit Gustavia weather in August.
In comparing the weather of September and October, we see a slight decrease in both average temperature and precipitation. September typically experiences higher humidity at 80%, with an average temperature of 28°C (82°F) and 152 mm (6.0 in) of rain over 22 days. In contrast, October's temperatures remain similar with a slight drop to an average of 27°C (81°F), but the rainfall decreases to 113 mm (4.4 in) across 19 days, and humidity eases to 79%. Overall, October offers a marginally drier experience while maintaining warm temperatures. For more detailed information, check out Gustavia weather in October.
In comparing the weather between September and November, September tends to be slightly warmer with temperatures ranging from a minimum of 25°C (77°F) to a maximum of 29°C (85°F), while November's temperatures are a bit cooler, with a range from 24°C (76°F) to 28°C (83°F). Additionally, September experiences significantly higher precipitation, totaling 152 mm (6.0 in) across 22 days, compared to November's 95 mm (3.8 in) over 17 days. Humidity levels are quite similar, with September at 80% and November at 79%. For more specifics on the weather conditions in November, you can check out Gustavia weather in November.
In September, the weather is notably warmer with average temperatures peaking at 28°C (82°F) and a maximum of 29°C (85°F), while the humidity remains high at 80%. This month also sees substantial rainfall of 152 mm (6.0 in) spread over 22 days, making it one of the wetter months. In contrast, December experiences milder temperatures, with a maximum of 28°C (82°F) and an average of 26°C (79°F). Precipitation significantly decreases to 48 mm (1.9 in) across 17 days, and humidity drops slightly to 78%. For a detailed look at Gustavia's weather during this time, you can check Gustavia weather in December.
As September rolls in, Gustavia experiences a distinctive shift in weather compared to the sunnier, drier months of the summer. The temperatures remain warm, hovering in the upper 20s, yet the island sees an increase in humidity and precipitation, with nearly three-quarters of the month receiving rain on average. This combination can create a lush, tropical atmosphere, though it also marks the transition to the wetter season. While you may encounter more wet days, the balmy temperatures and vibrant scenery make Gustavia an inviting destination even in September. For more insights on what to expect throughout the year, be sure to check out Gustavia Climate.