September Weather in Saint Simons Island, United States

Last updated: February 24, 2025

September on Saint Simons Island offers a warm and humid atmosphere, with average temperatures around 27°C (80°F) and daytime highs reaching up to 32°C (90°F). Mornings and evenings provide a refreshing contrast, dropping to a cool 19°C (66°F). This month is notable for its significant rainfall, accumulating about 166 mm (6.5 in) over approximately 15 days, making it essential for visitors to keep an eye on the weather. With humidity levels averaging a notable 83%, the island's lush landscapes are beautifully vibrant, inviting exploration between the occasional rain showers.

September Temperature in Saint Simons Island

As summer gently transitions to fall, September brings a delightful warmth to Saint Simons Island. With minimum temperatures around 19°C (66°F) and impressive highs reaching up to 32°C (90°F), the island enjoys a sweet spot of warmth that's perfect for beachgoers and outdoor enthusiasts alike. The average temperature settles at a pleasant 27°C (80°F), making it one of the most enjoyable months of the year. Unlike the sweltering days of July and August, September offers a balance of sunshine and comfort, allowing visitors to relish the beauty of the island without the peak summer heat. This seasonal shift not only enhances the island's picturesque landscapes but also invites a more relaxed atmosphere, making it an ideal time for exploration and recreation.

September Weather in Saint Simons Island: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Saint Simons Island, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec555862687479818180756558
Data source: Temperature data for Saint Simons Island generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Saint Simons Island

In September, Saint Simons Island experiences a notable surge in precipitation, with an average of 166 mm (6.5 in) over 15 days of rain. This spike is the highest monthly total for the year, signaling the peak of the summer rainy season. Following July and August, which also recorded substantial rainfall of 136 mm, September completes a trend of increased precipitation during the late summer months. The pattern suggests a shift towards wetter conditions, which may be attributed to tropical storms and atmospheric changes typical of this time of year, paving the way for a transition into the drier fall months ahead.

September Precipitation Trends in Saint Simons Island

The chart displays monthly precipitation patterns in Saint Simons Island, with values for each month alongside September's data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September's conditions compare to those of other months.
JanFebMarAprMayJunJulAugSepOctNovDec61936078651031361361668299121
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Saint Simons Island

September brings an increased humidity level to Saint Simons Island, clocking in at 83%. This slight uptick follows the highs of summer, where July and August maintain a consistent humidity of 82%. As autumn approaches, the humidity begins to shift, yet September remains notably damp, standing out from the drier months of April and May, both recorded at 72%. Interestingly, while humidity does dip in October to 79%, the overall trend throughout the year shows a tendency towards higher moisture levels, with January and December peaking at 84% and 85% respectively. This rhythm of humidity not only shapes the climate but also adds to the island's lush, vibrant atmosphere.

September Average Humidity in Saint Simons Island

This chart illustrates the average monthly humidity levels in Saint Simons Island, with September's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how September's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec84%79%78%73%72%74%82%82%83%79%82%85%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Saint Simons Island

As September unfolds in Saint Simons Island, the UV Index remains a prominent factor for sun seekers, showing a notable 10, which classifies exposure as very high and indicates a burn time of just 15 minutes. This marks a slight decrease from the extreme levels experienced during the summer months of June through August. However, the trend of heightened UV exposure continues, reminding residents and visitors alike to stay vigilant and protect their skin. As we transition into fall, the UV Index gradually descends, yet September's sunshine still warrants caution, especially for outdoor activities. For more detailed information, you can check the Saint Simons Island UV Index.

Maximum UV Index Levels in Saint Simons Island for September

The chart shows the monthly maximum UV Index (UVI) for Saint Simons Island in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec579101111111110864
Data source: Saint Simons Island September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

September Sunshine in Saint Simons Island

As summer gracefully transitions into fall, September shines brightly on Saint Simons Island with an impressive 302 hours of sunlight. This marks a slight dip from the peak sunlight of July, which boasts 347 hours, yet September retains a glorious warmth that envelops the island after the bustling summer months. With greater sunshine than the earlier months of the year, including January and February, visitors can bask in the lingering summer vibes while enjoying outdoor activities amidst the natural beauty of this coastal gem. Just as the leaves may soon begin to change, September serves as a perfect bridge, providing ample sunlight and pleasant temperatures for exploration and relaxation before the cooler days of October set in.

Monthly Sunshine Duration in Saint Simons Island: September Highlighted

The September sunshine duration represents the total number of hours Saint Simons Island experiences direct sunlight during the month of September, excluding cloudy or obstructed periods. This chart compares the sunshine duration of September with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec199h220h297h312h338h317h347h322h302h295h248h231h
Data source: Saint Simons Island September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Saint Simons Island During September

In September, Saint Simons Island enjoys a 47% chance of sunny weather, making it one of the more favorable months for sunshine after the summer season. This figure positions September as a transition month, slightly above June, July, and August, which experience lower probabilities of sun. Interestingly, the likelihood of sunny days begins to rise again in October and November, both peaking at 52% and 55% respectively. This pattern suggests that as the summer heat fades, the chances for brighter skies increase, inviting visitors to enjoy the serene beauty of the island as it shifts into the fall season.

Percentage of Sunny Days in September in Saint Simons Island

The chart illustrates the percentage of sunny days in Saint Simons Island throughout the year, with September highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Saint Simons Island experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec44%38%39%54%52%21%31%23%47%52%56%45%
Data source: Saint Simons Island September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Saint Simons Island in September

As summer gives way to fall, Saint Simons Island experiences a gradual but noticeable shift in daylight duration throughout September. With an average of 12 hours of daylight, the island begins to transition from the longest days of summer—where June boasts a generous 14 hours—to the shorter days ahead in October and November, each offering 11 hours. This month signifies a sweet spot as daylight remains abundant, yet hints at the impending cozy atmosphere of autumn. The slight decrease from August’s 13 hours captures the essence of changing seasons, making September a perfect time to enjoy the warm days as they slowly wane into the evening shadows.

Average Daylight Hours in Saint Simons Island for September

The chart illustrates the variation in daylight duration in Saint Simons Island throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec10h 22m11h 4m12h12h 56m13h 44m14h 7m13h 54m13h 12m12h 18m11h 22m10h 33m10h 8m
Data source: Saint Simons Island daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Saint Simons Island

In September, the winds in Saint Simons Island gently whisper at an average speed of 4.3 m/s (10 mph), marking a subtle decline from the summer months where breezes remained more robust at 4.6 m/s in both July and August. This easing of wind reflects the transition into autumn, as temperatures cool and tropical storms start to recede. Overall, September’s lighter gusts resonate with the island's tranquil charm, offering a serene backdrop for leisurely activities. Throughout the year, winter and spring months usher in crisper winds, peaking in March with 5.8 m/s, but as we approach the end of summer, the wind tends to mellow, creating perfect conditions for relaxation by the coast.

Average September Wind Speed in Saint Simons Island

The chart displays monthly wind speed patterns in Saint Simons Island, with values for each month shown alongside September's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how September's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec5.25.35.85.15.75.44.64.64.3 m/s4.55.44.7
Data source: Saint Simons Island September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Saint Simons Island Compares to Other Months

The weather in Saint Simons 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 Saint Simons Island and find detailed weather information for every month.

When comparing the weather in September and January, a stark contrast emerges. September boasts warmer temperatures, with a minimum of 19°C (66°F) and an average of 27°C (80°F), peaking at a maximum of 32°C (90°F). This month also experiences higher precipitation, with 166 mm (6.5 in) spread over 15 days, contributing to the humid conditions at 83%. In contrast, January presents a much cooler climate, featuring a minimum temperature of 0°C (33°F) and an average of 13°C (55°F), reaching a high of only 23°C (73°F). Precipitation in January is significantly lower at 61 mm (2.4 in) across just 6 days, and the humidity remains relatively high at 84%. For those interested in exploring January weather in detail, you can find more information here: Saint Simons Island weather in January.

September and February present contrasting weather patterns. In September, temperatures range from a mild 19°C (66°F) to a warm 32°C (90°F), with an average of 27°C (80°F). This month also experiences significant rainfall, averaging 166 mm (6.5 in) over 15 days, paired with high humidity levels at 83%. In stark contrast, February has cooler temperatures, with a minimum of 4°C (40°F) and a maximum of 21°C (71°F), averaging just 14°C (58°F). Precipitation in February is lower at 93 mm (3.6 in) across 11 days, and humidity is slightly reduced at 79%. For more detailed insights into February weather, visit Saint Simons Island weather in February.

When comparing the weather in September and March, notable differences emerge. September typically boasts a warm climate, with temperatures ranging from a minimum of 19°C (66°F) to a maximum of 32°C (90°F), while averaging 27°C (80°F). This month also experiences higher precipitation, with 166 mm (6.5 in) falling over 15 days, resulting in a humid atmosphere with an average humidity of 83%.

In contrast, March brings a cooler and more temperate climate, with temperatures varying from a minimum of 5°C (41°F) to a maximum of 24°C (76°F), averaging around 16°C (62°F). The precipitation is notably less, at 60 mm (2.4 in) over only 6 days, and the humidity is slightly lower at 78%. For more details on March weather, check out Saint Simons Island weather in March.

When comparing the weather in September and April, notable differences emerge in temperature and humidity. September tends to be warmer, with average temperatures around 27°C (80°F) and a maximum of 32°C (90°F), while April is cooler with averages of 20°C (68°F) and a high of 28°C (82°F). In terms of precipitation, September sees significantly more rainfall, totaling 166 mm (6.5 in) over about 15 days, compared to April's 78 mm (3.1 in) which occurs over just 7 days. Additionally, humidity levels are higher in September at 83%, compared to April's 72%. For a detailed look at the weather specifics in April, check out Saint Simons Island weather in April.

September generally experiences warmer temperatures compared to May, with average daily highs reaching up to 32°C (90°F) versus May’s 30°C (86°F). The humidity in September is notably higher at 83%, contributing to a more muggy atmosphere than May’s 72%. Furthermore, September is characterized by significantly more rainfall, receiving 166 mm (6.5 in) over about 15 days, while May sees only 65 mm (2.6 in) over 8 days. For a detailed look at May’s weather, you can refer to Saint Simons Island weather in May.

In comparing the weather between September and June, September tends to be slightly warmer, with average temperatures ranging from 19°C (66°F) to a maximum of 32°C (90°F). In contrast, June's temperatures start a bit higher, with a minimum of 20°C (68°F) and a maximum reaching 31°C (89°F). June experiences less precipitation, with an average of 103 mm (4.1 in) over 14 days, compared to September's 166 mm (6.5 in) over 15 days. Additionally, September has higher humidity at 83% compared to June's 74%. For more details on the June weather, visit Saint Simons Island weather in June.

When comparing the weather in September to that of July, several distinctions emerge despite the similar average temperatures. In September, the minimum temperature is slightly lower at 19°C (66°F), while July starts at a warmer minimum of 24°C (76°F). Both months share the same average maximum temperature of 32°C (90°F in September, 89°F in July), but September experiences more rainfall, with 166 mm (6.5 in) over 15 days, compared to July's 136 mm (5.3 in) spread over 16 days. Humidity levels are slightly higher in September at 83%, compared to July’s 82%. For more details on July weather, you can check Saint Simons Island weather in July.

In comparing the weather between August and September, both months exhibit similar average temperatures, with September averaging 27°C (80°F) and August at 27°C (82°F). However, September tends to be slightly cooler at night, with a minimum temperature of 19°C (66°F) compared to August's minimum of 24°C (76°F). Precipitation is more frequent in September, occurring over 15 days, leading to a total of 166 mm (6.5 in) of rainfall, while August sees less precipitation at 136 mm (5.4 in) spread over 19 days. Humidity levels are also similar, with September at 83% and August at 82%. For more specific details about the weather dynamics in August, you can visit this link: Saint Simons Island weather in August.

September weather is characterized by warmer temperatures, with a minimum of 19°C (66°F) and an average of 27°C (80°F), peaking at 32°C (90°F). It also sees significant rainfall, with 166 mm (6.5 in) spread over 15 days and high humidity at 83%. In contrast, October brings a notable drop in temperatures, with a minimum of 11°C (51°F) and an average of 24°C (75°F), reaching a maximum of 30°C (86°F). Precipitation decreases to 82 mm (3.2 in) over 11 days, and humidity also slightly lowers to 79%. For more details on the specific weather patterns, visit Saint Simons Island weather in October.

September and November present contrasting weather patterns. In September, temperatures range from a minimum of 19°C (66°F) to a warm maximum of 32°C (90°F), with an average of 27°C (80°F). This month is marked by high humidity at 83% and significant rainfall, totaling 166 mm (6.5 in) over approximately 15 days. In stark contrast, November brings cooler temperatures, with a minimum of 5°C (41°F), an average of 18°C (65°F), and a maximum of 27°C (80°F). Rainfall is also reduced, with only 99 mm (3.9 in) over about 7 days. Humidity remains similar, at 82%. For more detailed information on the climate, you can check Saint Simons Island weather in November.

September and December present contrasting weather patterns, showcasing the transition from late summer to early winter. In September, temperatures are warm, with a minimum of 19°C (66°F) and an average of 27°C (80°F), reaching a maximum of 32°C (90°F). The month also sees significant rainfall, with 166 mm (6.5 in) of precipitation over 15 days, coupled with high humidity of 83%. In contrast, December ushers in much cooler temperatures, with a minimum of 3°C (37°F) and an average of 15°C (59°F), peaking at a comfortable 22°C (72°F). The precipitation decreases to 121 mm (4.8 in) over just 10 days, while humidity rises slightly to 85%. For a more detailed look at the weather in December, check out Saint Simons Island weather in December.

Compare Saint Simons Island's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Saint Simons Island

As September unfolds on Saint Simons Island, it marks a transition towards milder conditions compared to the sweltering summer months. While temperatures remain warm with an average around 27°C (80°F), the increasing humidity at 83% can make it feel particularly sticky. Frequent rain showers, occurring on approximately 15 days throughout the month, lead to a significant accumulation of 166 mm (6.5 in) of precipitation, providing a refreshing break from the heat. This combination of warmth and moisture sets September apart as a unique time for both locals and visitors to experience the island's lush landscapes and vibrant flora. For a deeper dive into the seasonal trends and variations, check out the comprehensive guide on Saint Simons Island Climate.