Last updated: October 31, 2025
September in Koolbaai, Sint Maarten, offers a tropical experience characterized by warm temperatures and a vibrant atmosphere. With maximum temperatures reaching 29°C (85°F) and an average of 28°C (82°F), visitors can expect balmy days perfect for leisure. The minimum nighttime temperatures dip to a comfortable 25°C (77°F). While this month does experience precipitation, with a total of 161 mm (6.3 in) spread over 22 rainy days, the island's lush landscapes thrive. Humidity levels hover around 80%, adding to the sultry essence of the Caribbean. Embrace the warm, tropical climate of Koolbaai, where each rain shower is just a reminder of nature's beauty.
In September, Koolbaai, Sint Maarten continues to bask in the warmth of the Caribbean, with temperatures reflecting a steady trend of tropical bliss. The month features a minimum temperature of 25°C (77°F), while the average climbs to a balmy 28°C (82°F), peaking at a comfortable 29°C (85°F) during the day. This maintains the pattern established in August, where warm days seamlessly merge into cooler nights, ensuring that the evenings remain pleasant for outdoor activities. As summer begins to transition into fall, September's temperatures not only invite beachgoers but also represent a harmonious consistency in the island's tropical climate, making it an inviting destination for those seeking sun-soaked adventures.
September in Koolbaai, Sint Maarten, is marked by a significant surge in precipitation, with 161 mm (6.3 in) of rain falling over 22 days. This month stands out as the wettest of the year, showcasing a dramatic increase compared to the preceding months, where rainfall ranged consistently from 27 mm to 87 mm. The rainfall during September not only surpasses previous months but also reflects the onset of the Caribbean's wet season, contributing to lush landscapes and vibrant flora. As the island transitions into October, the precipitation amount notably decreases to 113 mm (4.5 in), hinting at a gradual shift towards drier conditions while still retaining a substantial number of rainy days. This trend underscores the importance of September in the annual climatic cycle of Koolbaai, serving as a pivotal moment in the region's weather patterns.
In September, Koolbaai, Sint Maarten experiences a slight dip in humidity at 80%, following the peak summer months of July and August, where humidity reached 83% and 82%, respectively. This trend indicates that while September remains humid, the transition into fall brings about a gradual decline in moisture levels compared to the sweltering summer days. Notably, the humidity has been on an upward trajectory since April, but as the year progresses toward October, it begins to stabilize around the 79% mark. Such fluctuations contribute to the island’s tropical allure, blending warmth and discomfort in a captivating dance of climate.
In September, Koolbaai, Sint Maarten experiences a noteworthy rise in the UV Index to 14, marking it as extreme and requiring caution for sun exposure. This increase aligns with a trend observed throughout the summer months, where the UV Index remains consistently high at 13, demanding a burn time of just 10 minutes. As the island transitions from the steamy summer to the milder autumn, maintaining awareness of sun safety becomes crucial. With burn times remaining low throughout this period, visitors and residents alike should prioritize sun protection. For detailed insights, you can explore more at Koolbaai UV Index.
UV Risk Categories
As the summer months wane, September in Koolbaai, Sint Maarten still treats residents and visitors to a delightful 322 hours of sunshine. While this marks a gentle dip from the sun-soaked days of May and July, which each basked in over 360 hours, it stands as a testament to the island's consistent warmth even as the seasons transition. Notably, September's sunshine is comparable to its immediate predecessors, maintaining a vibrant atmosphere that invites relaxation and adventure. This trend of abundant sunshine continues through the fall, as both October and November promise similar sunlit hours, ensuring that the island remains a sun-kissed paradise year-round.
September in Koolbaai, Sint Maarten, offers a 58% chance of sunny weather, marking a notable transition from the more overcast summer months. As the peak of the Caribbean summer fades, the likelihood of sun begins to rise, moving away from June's low of just 25%. This shift reflects a broader trend of improving weather patterns as autumn approaches, with September showcasing a favorable balance that can entice visitors seeking to enjoy idyllic beach days. Following September, sunny days remain mostly consistent through the fall, with October and November boasting 56% and 67% chances, respectively, ensuring that the sun shines brightly on the picturesque shores of Koolbaai during this enchanting time of year.
In Koolbaai, Sint Maarten, September delights with approximately 12 hours of daylight, mirroring the trend seen in August. As summer gradually transitions into autumn, the daylight duration remains stable, reflecting the island's consistent tropical climate. From January to April, daylight steadily increases, reaching its peak in June and July with 13 hours of glorious sun. However, as the year progresses towards the end, daylight hours diminish again, dropping to 11 hours in October through December. This rhythmic pattern enhances the island's charm, ensuring that each month offers its fair share of sunshine for both residents and visitors alike.
As September rolls into Koolbaai, Sint Maarten, the wind takes a gentle turn, with average speeds dipping to 5.3 m/s (12 mph). This marks a notable reduction from the summer peak observed in July and August, where breezes danced at 8.5 m/s (19 mph) and 7.2 m/s (16 mph) respectively. The transition into autumn brings a serene calmness, creating an inviting atmosphere for relaxation. Interestingly, this seasonal shift is part of a broader trend where the wind often softens during the late summer months, only to pick up again as the year progresses into October and December, which typically see winds increasing to 6.3 m/s (14 mph) and 8.1 m/s (18 mph) respectively. This ebb and flow of the winds not only enhances the charm of coastal life but also sets a picturesque backdrop for the tranquil September days in Koolbaai.
Weather in Koolbaai varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Koolbaai, focusing on differences in temperature, rainfall, humidity, and UV levels.
September weather is typically warmer and wetter compared to January. The average temperature in September reaches around 28°C (82°F), with highs of 29°C (85°F), while January sees a slightly cooler average of 25°C (78°F) and max temperatures of 27°C (81°F). Additionally, September experiences significantly more rainfall with 161 mm (6.3 inches) over 22 days, contrasted with January's much drier conditions of just 35 mm (1.4 inches) over 14 days. Humidity levels are also marginally higher in September at 80%, compared to January's 77%. For a more detailed look at January's weather, you can check out Koolbaai weather in January.
In September, the weather tends to be warmer and wetter, with average temperatures around 28°C (82°F) and high humidity levels of 80%. This month experiences significant rainfall, totaling 161 mm (6.3 in) spread over 22 days, making it quite a rainy period. In contrast, February offers milder conditions, with average temperatures dropping to 25°C (77°F) and lower humidity at 77%. The precipitation is significantly reduced to just 35 mm (1.4 in) over 11 days, allowing for more dry and pleasant outings. For a detailed look at February weather, you can refer to Koolbaai weather in February.
In September, the weather is characterized by warmer temperatures, with a minimum of 25°C (77°F) and an average high of 29°C (85°F). The month is also quite wet, receiving about 161 mm (6.3 in) of precipitation over 22 days, contributing to a high humidity level of 80%. In contrast, March offers milder conditions, with temperatures ranging from a minimum of 22°C (73°F) to a maximum of 26°C (79°F). This month sees significantly less rainfall, with only 27 mm (1.1 in) spread over just 10 days, and a slightly lower humidity of 77%. To explore more about the weather in March, you can visit Koolbaai weather in March.
September and April exhibit notable differences in weather patterns. September tends to be warmer with an average temperature of 28°C (82°F), while April is slightly cooler at an average of 25°C (78°F). Furthermore, September is characterized by significantly higher precipitation, receiving 161 mm (6.3 in) over 22 days, compared to April's modest 35 mm (1.4 in) over just 11 days. Humidity levels are similarly high throughout both months, with September at 80% and April slightly lower at 78%. For more specific insights on April weather, you can visit Koolbaai weather in April.
In comparing the weather between September and May, we find notable differences in temperature and precipitation. September typically experiences warmer conditions, with average temperatures peaking at 28°C (82°F) and maxing out at 29°C (85°F), whereas May boasts slightly cooler averages with a maximum of 28°C (82°F) and a minimum of 23°C (74°F). Precipitation also varies significantly; September receives a substantial 161 mm (6.3 in) of rain over 22 days, while May is much drier, with only 49 mm (1.9 in) over 11 days. Despite these distinctions, both months exhibit high humidity levels, hovering around 80% in September and 79% in May, contributing to the overall tropical feel. For more detailed insights on May weather, you can check Koolbaai weather in May.
In comparing the weather between September and June, both months showcase warm temperatures, with minimums around 25°C (77°F) and average highs close to 29°C (85°F) in September and 28°C (83°F) in June. However, September experiences significantly more precipitation, with 161 mm (6.3 in) over 22 days, compared to June's 50 mm (2.0 in) across 14 days. Humidity levels are quite similar, with September at 80% and June at 81%, making both months feel similarly muggy despite the differences in rainfall. For a detailed look at June conditions, check out Koolbaai weather in June.
In comparing the weather of September and July, we notice that both months share similar temperature ranges, with September slightly warmer on average, at 28°C (82°F) compared to July's average of 27°C (81°F). However, September is considerably wetter, receiving 161 mm (6.3 in) of precipitation over 22 days, whereas July experiences much less rainfall, with only 83 mm (3.3 in) over 17 days. Additionally, humidity levels are similar, with September at 80% and July slightly higher at 83%. This means that while both months feature warm temperatures, September is notably more humid and rainy. For a more detailed look at July weather, you can visit Koolbaai weather in July.
In comparing the weather of September to August, we find that both months feature similar temperature ranges, with September displaying a minimum of 25°C (77°F) and an average of 28°C (82°F), identical to August. However, September experiences significantly more precipitation, totaling 161 mm (6.3 inches) over 22 days, compared to August’s 87 mm (3.4 inches) over 16 days. Additionally, humidity is slightly lower in September at 80%, while it hovers around 82% in August. For a detailed look at the weather specifics for August, visit Koolbaai weather in August.
September and October exhibit similar warm temperatures, with September averaging 28°C (82°F) and October slightly cooler at 27°C (81°F). Both months experience minimum temperatures around 25°C (77°F) and maximums nearing 29°C (85°F). However, September is notably wetter, with 161 mm (6.3 in) of precipitation over 22 days, compared to October's 113 mm (4.5 in) over 18 days. Humidity levels remain high but slightly decrease from 80% in September to 79% in October. For more detailed insights, you can check Koolbaai weather in October.
September and November offer distinct variations in weather patterns. In September, temperatures are generally warmer, with a minimum of 25°C (77°F) and an average high of 29°C (85°F). This month also witnesses significant rainfall, with a total precipitation of 161 mm (6.3 in) over 22 days, contributing to a humid atmosphere with an average humidity of 80%.
In contrast, November brings slightly cooler temperatures, with a minimum of 24°C (76°F) and an average maximum of 28°C (83°F). The month sees a decrease in precipitation to 96 mm (3.8 in) over 17 days, and the humidity remains comfortably around 79%. For a detailed insight into November weather patterns, you can check out Koolbaai weather in November.
In September, the weather is notably warmer with temperatures ranging from a minimum of 25°C (77°F) to a maximum of 29°C (85°F) and an average of 28°C (82°F). This month also experiences significant rainfall, with 161 mm (6.3 in) spread over 22 days, accompanied by high humidity levels of 80%. In contrast, December presents a slightly cooler climate, where temperatures range from a minimum of 24°C (75°F) to a maximum of 28°C (82°F), with an average temperature of 26°C (79°F). Rainfall in December is considerably less, totaling 48 mm (1.9 in) across 16 days, and humidity remains relatively low at 78%. For more detailed information about the weather in Koolbaai during December, you can check this link: Koolbaai weather in December.
As September unfolds in Koolbaai, the weather embraces a warm, tropical charm that sets it apart from other months. With average temperatures hovering around 28°C (82°F) and maximums reaching a delightful 29°C (85°F), this month provides a pleasant warmth ideal for beach-goers and nature lovers alike. However, September also marks the peak of rainfall, with 161 mm (6.3 in) spread over 22 days, bringing much-needed moisture to the lush surroundings. This combination of humidity at 80% and increased precipitation creates a vibrant, green landscape, though visitors should be prepared for occasional showers. For a deeper understanding of the seasonal trends, check out Koolbaai Climate.