Last updated: February 24, 2025
September on Sullivan's Island, United States offers a warm retreat with maximum temperatures reaching 32°C (90°F) and an average of 26°C (79°F). While visitors can enjoy the balmy climate, they should be prepared for occasional rain, as the month typically sees 188 mm (7.4 in) of precipitation over about 14 days. The 81% humidity adds a tropical feel to the air, creating a vibrant backdrop for beach activities and exploration. Embrace the warm, yet somewhat unpredictable, early autumn weather of this charming coastal destination.
In September, Sullivans Island experiences a delightful transition towards the end of summer, characterized by a minimum temperature of 16°C (61°F) and a comfortable average of 26°C (79°F). As the month unfolds, daytime highs peak at a sizzling 32°C (90°F), making it one of the warmer months in the year. This warm climate invites outdoor activities along the scenic coastline, while the evenings offer a refreshing respite. Compared to the preceding months, September maintains the warmth with a slight decrease in minimum temperatures, hinting at the cooler days ahead as autumn approaches. Overall, this month serves as a perfect blend of lingering summer heat and the first whispers of fall, beckoning visitors to enjoy the vibrant beach atmosphere before the cooler temperatures take hold.
In September, Sullivans Island experiences a notable shift in precipitation patterns, receiving 188 mm (7.4 in) of rain over approximately 14 days. This amount reflects a marked decrease from the peak of 197 mm (7.8 in) recorded in August, indicating a gradual transition as summer fades. While rainfall remains substantial, it falls behind the intense summer months, where June and July collectively harness more than 300 mm of rain. This trend suggests a shift towards the drier conditions that characterize the upcoming months, with October seeing a significant decline to 85 mm (3.4 in). As September settles in, residents can expect a mix of rainy days and lingering warmth, setting the stage for the autumn season ahead.
September in Sullivans Island sees a humidity level of 81%, maintaining the trend of elevated moisture that begins in late summer. As the sweltering days of July and August give way to more temperate conditions, the humidity slightly drops but remains relatively high, comparable to the levels observed in earlier months like January and November. This consistency in humidity creates a warm, tropical atmosphere that characterizes the coastal climate, hinting at the lingering effects of summer while foreshadowing the gradual easing into the cooler autumn months. Overall, September's humidity aligns with the island's typical annual patterns, where moisture levels fluctuate lightly yet remain a defining feature of the environment.
As September rolls into Sullivans Island, the UV Index remains notably high at 9, categorizing it as very high exposure with a burn time of just 15 minutes. This trend follows the extreme levels seen during the peak summer months, where July reached a staggering UV Index of 12. While there is a slight decrease from August’s UV Index of 11, the sun’s intensity continues to demand caution. Residents and visitors alike should stay vigilant, donning protective clothing and sunscreen during outdoor activities. As we transition into autumn, understanding these fluctuations in UV exposure is essential for skin safety. For more detailed information, you can check here: Sullivans Island UV Index.
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September in Sullivan's Island ushers in a delightful change as summer fades, boasting an impressive 304 hours of sunshine. This month continues to showcase the region’s abundant sunlight, despite a slight dip from July's peak of 345 hours. As we transition from the sun-drenched days of summer, September maintains a robust brightness, contributing to a total that outshines the winter months ahead. After reaching a zenith in late spring, the gradual decline in sunshine hours reflects the seasonal shift, making September a perfect time to enjoy the lingering warmth and vibrant outdoor activities before the cooler autumn days take hold.
September in Sullivan's Island brings a promising 52% chance of sunny weather, making it a delightful time to soak up the sun before the cooler months set in. As summer wanes, the likelihood of sunny days shows a noticeable improvement from the dreary summer months of June and August, which only offered a 30% and 32% chance of sunshine, respectively. This trend continues into October, maintaining a healthy 50% probability of clear skies. With September's moderate warmth and increasing sunshine, it's an ideal month for outdoor activities, encouraging residents and visitors alike to embrace all that this charming coastal town has to offer. Enjoy the sunny forecast while it lasts!
As September arrives on Sullivans Island, the golden days of summer begin to wane, bringing a gentle reduction in daylight. With 12 hours of sunlight, this month marks a transition from the longer, sun-drenched days of summer, when July and June bask in 14 hours, to the shorter days of fall and winter. As the year progresses, daylight steadily decreases, with October ushering in a further decline to 11 hours. This rhythmic ebb and flow of sunlight not only highlights the changing seasons but also invites residents and visitors to savor the last warm days of the year before the tranquility of autumn settles in.
As September rolls into Sullivans Island, the coastal breezes begin to soften, with an average wind speed dipping to 4.0 m/s (9 mph). This marks a notable decline from the warmer summer months, where July and August experienced lower winds of 4.4 m/s (10 mph) and 3.9 m/s (9 mph), respectively. The transition into fall brings a gentle rustle of leaves and a serene atmosphere, setting the stage for more tranquil outdoor experiences. While wind speeds tend to fluctuate throughout the year, September signals a shift towards the calmer days ahead, hinting at the returning stability of autumn. As summer's heat fades, the refreshing winds may serve as a gentle reminder to embrace the changing seasons on this picturesque island.
The weather in Sullivans Island changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of September's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Sullivans Island and find detailed weather information for every month.
September and January present stark contrasts in weather. In September, temperatures range from a mild 16°C (61°F) to a high of 32°C (90°F), with an average of 26°C (79°F), while the humidity remains elevated at 81%. The month also sees significant rainfall, with 188 mm (7.4 in) spread over 14 days. In contrast, January experiences much cooler temperatures, with a minimum of -5°C (24°F), an average of 12°C (53°F), and a maximum of 21°C (70°F). Precipitation decreases to 66 mm (2.6 in) over only 8 days, and humidity is slightly higher at 83%. For more details, check out Sullivans Island weather in January.
September and February present stark contrasts in weather conditions. In September, temperatures are much warmer, with a minimum of 16°C (61°F) and an average of 26°C (79°F), peaking at 32°C (90°F). The month also sees significant precipitation of 188 mm (7.4 in) over approximately 14 days, accompanied by high humidity at 81%. In contrast, February is cooler, with minimum temperatures dropping to 2°C (36°F) and averages around 14°C (57°F), reaching a maximum of 21°C (70°F). This month experiences far less rainfall, totaling 91 mm (3.6 in) over 11 days, and a slightly lower humidity level of 79%. For a more detailed look at February conditions, you can refer to Sullivans Island weather in February.
In September, the weather tends to be much warmer and more humid compared to March. With minimum temperatures around 16°C (61°F) and maximums reaching up to 32°C (90°F), September showcases an average of 26°C (79°F). However, this month also brings considerable rainfall, with about 188 mm (7.4 in) of precipitation over 14 days and humidity levels around 81%. In contrast, March is cooler, featuring minimum temperatures of 2°C (36°F) and a maximum of 23°C (74°F), with an average temperature of 15°C (60°F). Precipitation is significantly lower in March, totaling about 62 mm (2.4 in) over just 7 days, and humidity is slightly less at 79%. For more details on the March weather specifics, you can check Sullivans Island weather in March.
September and April exhibit distinct weather patterns, each with its unique characteristics. In September, temperatures range from a minimum of 16°C (61°F) to a maximum of 32°C (90°F), averaging around 26°C (79°F), making it notably warmer than April. The month also sees significant rainfall, with 188 mm (7.4 in) of precipitation spread over 14 days and a humidity level of 81%. In contrast, April experiences milder temperatures, with a minimum of 6°C (42°F) and a maximum of 27°C (81°F), averaging 19°C (66°F). The precipitation during this month is lower, at 105 mm (4.1 in) over 8 days, and humidity is slightly less at 78%. For a closer look at the weather specifics in April, check out Sullivans Island weather in April.
When comparing the weather in September and May, we see notable differences in temperature and precipitation. September tends to be warmer, with average temperatures reaching 26°C (79°F), peaking at 32°C (90°F), while May features slightly cooler averages at 23°C (74°F) with a maximum of 31°C (89°F). Additionally, September experiences significantly higher precipitation, measuring 188 mm (7.4 in) over 14 days, compared to May's 82 mm (3.2 in) over just 8 days. Humidity levels are fairly similar, with September at 81% and May at 78%. For more details on May weather, visit Sullivans Island weather in May.
When comparing the weather in September and June, both months offer similar average temperatures, hovering around 26°C (79°F), with maximum temperatures reaching up to 32°C (90°F). However, September tends to be slightly cooler on the lower end, starting at a minimum of 16°C (61°F) compared to June's 18°C (64°F). Additionally, September experiences higher precipitation levels, totaling 188 mm (7.4 in) over 14 days, while June has less rainfall at 144 mm (5.7 in) spread across 17 days. Humidity levels are also a bit elevated in September at 81%, compared to June's 78%. For more localized details, you can check Sullivans Island weather in June.
In comparing the weather of September and July, we see some notable differences. September tends to have slightly cooler minimum temperatures, averaging 16°C (61°F) compared to July's 22°C (72°F). However, both months see maximum temperatures peaking at around 32°C (90°F). September receives more precipitation, with 188 mm (7.4 in) falling over 14 days, while July has 171 mm (6.7 in) across 16 days, indicating a wetter but slightly less frequent rainfall. Humidity levels are similar, with September at 81% and July at 82%. For more detailed information about July weather conditions, you can check Sullivans Island weather in July.
In comparing the weather of September to August, we see a notable shift in temperature and precipitation patterns. September experiences slightly cooler temperatures, with an average of 26°C (79°F) compared to August's 27°C (81°F). The minimum temperature in September is also lower at 16°C (61°F), while August starts warmer at 23°C (73°F). Although September sees a reduction in maximum temperatures with a peak of 32°C (90°F) compared to August's 31°C (89°F), it has a longer stretch of rainy days, with precipitation occurring on 14 days in September versus 21 days in August. The overall precipitation amounts are relatively close, with September receiving 188 mm (7.4 in) and August 197 mm (7.8 in), maintaining the same humidity level of 81%. For more details on August weather, you can check Sullivans Island weather in August.
In September, the weather is significantly warmer, with temperatures ranging from a minimum of 16°C (61°F) to a maximum of 32°C (90°F), averaging around 26°C (79°F). This month also experiences more precipitation, totaling 188 mm (7.4 in) over 14 days, contributing to a high humidity level of 81%. In contrast, October sees a notable drop in temperatures, with a minimum of 7°C (46°F) and a maximum of 29°C (85°F), averaging 23°C (73°F). The rainfall decreases to 85 mm (3.4 in) over 10 days, with humidity slightly lower at 78%. For more details on the weather specifics, check out Sullivans Island weather in October.
September and November present contrasting weather experiences. In September, temperatures start off mild, with an average of 26°C (79°F) and highs reaching up to 32°C (90°F), while experiencing significant rainfall of 188 mm (7.4 in) over 14 days, contributing to high humidity levels of 81%. In contrast, November brings a noticeable drop in temperatures, with an average of 16°C (62°F) and maximums of 26°C (79°F), alongside reduced precipitation at 103 mm (4.1 in) spread over just 8 days. Despite the cooler temperatures, November maintains a similar humidity level at 82%. For detailed insights on weather conditions, check out Sullivans Island weather in November.
September and December present starkly contrasting weather conditions. In September, temperatures are significantly warmer, with an average of 26°C (79°F) and highs reaching up to 32°C (90°F), accompanied by high humidity at 81%. Rainfall is abundant, with about 188 mm (7.4 in) over 14 days. In contrast, December brings a chillier climate, with average temperatures dropping to 13°C (56°F) and daytime highs of only 22°C (72°F). Although December experiences slightly less rainfall, with 141 mm (5.6 in) spread over 10 days, the humidity remains high at 84%. For a detailed look at what to expect, you can check Sullivans Island weather in December.
As summer transitions into fall, September on Sullivans Island experiences a delightful blend of warmth and humidity. With average temperatures hovering around 26°C (79°F) and a maximum of 32°C (90°F), the air remains pleasantly balmy, though the humidity level rises to about 81%. This month also marks a notable shift in precipitation, seeing around 188 mm over approximately 14 days, which adds a refreshing contrast to the otherwise sunny days. Compared to the drier summer months, September brings a lush vibrancy, making it an ideal time for those seeking a lively beach atmosphere. For a deeper dive into the island's seasonal shifts, explore the Sullivans Island Climate.