September Weather in Sanibel, United States

Last updated: February 24, 2025

Sanibel, United States, experiences September weather characterized by warm temperatures and considerable moisture. The maximum temperature can reach a balmy 33°C (92°F), while the average temperature hovers around 28°C (82°F), making it an inviting destination for beachgoers. In contrast, the minimum temperatures fall to a comfortable 23°C (74°F) during the cooler nights. This month is marked by significant rainfall, totaling 169 mm (6.7 in) spread over approximately 20 days, contributing to the island's lush landscapes. With humidity levels averaging around 83%, the air is often thick with moisture, enhancing the tropical feel of this picturesque locale. Whether you’re exploring the stunning beaches or enjoying the vibrant wildlife, Sanibel’s September climate offers a unique experience for visitors.

September Temperature in Sanibel

September in Sanibel showcases the warm embrace of summer as temperatures continue to hover at pleasant levels. With a minimum of 23°C (74°F) and an average temperature of 28°C (82°F), the island remains a tropical haven. The maximum temperature can reach up to 33°C (92°F), making it one of the warmest months of the year. As summer fades, September still offers a delightful climate, perfect for beachgoers and outdoor adventurers alike. Notably, the trend of rising temperatures persists through the summer months, making this island retreat an ideal spot to soak up the sun before the cooler autumn days arrive.

September Weather in Sanibel: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Sanibel, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec656971757981828282807368
Data source: Temperature data for Sanibel 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 Sanibel

In September, Sanibel experiences a significant shift in weather patterns as precipitation remains robust, totaling 169 mm (6.7 in) over 20 days. This marks a decrease from the peak rainfall seen in August, which recorded 206 mm (8.1 in), yet still represents a notable continuation of the wet season that began in May. The interplay between humidity and frequent showers provides a lush environment, characteristic of the region during this transitional month. As summer gives way to autumn, September's rain keeps the surroundings vibrant and alive, making it a lush yet breezy time on the island. Despite fewer rain days compared to the preceding months of July and August, the steady rainfall ensures that Sanibel's natural beauty remains on full display, inviting visitors to indulge in the rich, tropical landscape.

September Precipitation Trends in Sanibel

The chart displays monthly precipitation patterns in Sanibel, 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.
JanFebMarAprMayJunJulAugSepOctNovDec36362242122170195206170774452
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Sanibel

In September, Sanibel experiences a notable increase in humidity, matching January's 83% humidity level. This month marks a return to more tropical conditions, as humidity levels rise from the mid to upper 70s experienced in the summer months of July and August. As the year progresses, it's evident that Sanibel's humidity tends to hover around the low to mid-80s during the fall and winter months, with the highest humidity levels occurring from December to March. The consistent humidity emphasizes the island's tropical climate, making Sanibel not only a captivating destination but also a humid one as it transitions into the autumn season.

September Average Humidity in Sanibel

This chart illustrates the average monthly humidity levels in Sanibel, 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.
JanFebMarAprMayJunJulAugSepOctNovDec83%80%75%68%65%73%77%80%83%83%83%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Sanibel

In September, Sanibel experiences a UV Index of 11, placing it in the extreme exposure category with a burn time of just 10 minutes. This slight decrease from August's peak index of 12 indicates that while the summer intensity wanes, strong UV radiation remains prevalent. The trend over the year reveals that Sanibel consistently faces high to extreme UV levels, especially from April through August, necessitating protective measures for sun-seekers. As autumn approaches, the shift to a slightly lower index in September reminds residents and visitors to stay vigilant about sun safety. For more details on this year-round UV exposure, explore the Sanibel UV Index.

Maximum UV Index Levels in Sanibel for September

The chart shows the monthly maximum UV Index (UVI) for Sanibel 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.
JanFebMarAprMayJunJulAugSepOctNovDec69101212121212111086
Data source: Sanibel 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 Sanibel

As summer gracefully transitions into fall, September in Sanibel shines with 313 hours of sunlight, continuing a trend of abundant sunshine that characterizes the region. Following the peak of 332 hours in July, the days gradually shorten, yet this month still offers a generous amount of bright skies. The sunlight recorded in September reflects a cozy warmth that invites outdoor activities, making it an ideal time for nature walks and beach outings. While the hours may dip slightly compared to the summer months, they still provide an enticing backdrop for enjoying the beauty of Sanibel Island, reinforcing its reputation as a sunlit paradise well into the autumn.

Monthly Sunshine Duration in Sanibel: September Highlighted

The September sunshine duration represents the total number of hours Sanibel 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.
JanFebMarAprMayJunJulAugSepOctNovDec225h277h328h325h329h303h332h326h313h301h276h288h
Data source: Sanibel September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Sanibel During September

As summer fades, September in Sanibel brings a notable shift in sunny weather, with a 35% chance of sunshine. This dip follows the high month of April, when the sun shines nearly two-thirds of the time, and comes after a series of summer months where the sun seems to retreat, boasting chances as low as 18% in August. While September does not offer the same sunlit promise as the spring months, it still provides a welcome reprieve from the oppressive heat, making it a worthwhile time to enjoy the beautiful scenery, albeit with a slightly greater chance of cloudy skies. As the month progresses, the likelihood gradually improves, hinting at the sunnier days ahead in October and November.

Percentage of Sunny Days in September in Sanibel

The chart illustrates the percentage of sunny days in Sanibel 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 Sanibel experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec46%61%59%65%56%19%21%18%35%49%53%64%
Data source: Sanibel September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Sanibel in September

As September rolls into Sanibel, the daylight hours begin to transition from the peak of summer. With 12 hours of daylight, this month marks a slight decline from the 13 hours experienced during the sun-soaked summer months of June through August. This gradual decrease in sunlight is a prelude to the forthcoming autumn, as daylight dims steadily through October. Interestingly, September maintains the length of daylight seen in both March and April, showcasing a balanced moment in the seasonal dance, where the warmth of summer lingers just before the cooler months approach. Enjoying Sanibel’s beaches under this golden September sun offers a perfect blend of warmth and light before the days grow shorter.

Average Daylight Hours in Sanibel for September

The chart illustrates the variation in daylight duration in Sanibel throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec10h 40m11h 15m12h 1m12h 47m13h 26m13h 45m13h 35m13h12h 16m11h 29m10h 49m10h 29m
Data source: Sanibel daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Sanibel

As September rolls in, Sanibel experiences a notable drop in wind speed, averaging just 2.7 m/s (6 mph), making it the calmest month of the year. This gentle breeze contrasts starkly with the brisker winds of the earlier months, like January's 3.8 m/s (9 mph) or the steady 4.4 m/s (10 mph) seen in May. The transition to September signifies a natural shift towards more tranquil weather, perfect for leisurely beach strolls or peaceful afternoons by the shore. Following the summer's moderate winds, this softer airflow invites both locals and visitors to embrace the island's serene charm as autumn begins to set in.

Average September Wind Speed in Sanibel

The chart displays monthly wind speed patterns in Sanibel, 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.
JanFebMarAprMayJunJulAugSepOctNovDec3.84.64.34.34.43.63.13.42.7 m/s3.74.13.0
Data source: Sanibel September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Sanibel Compares to Other Months

The weather in Sanibel 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 Sanibel and find detailed weather information for every month.

September and January exhibit striking contrasts in weather patterns. September typically experiences higher temperatures, with daily averages around 28°C (82°F) and peaks reaching up to 33°C (92°F), accompanied by significant rainfall of 169 mm (6.7 in) over 20 days. In stark contrast, January is much cooler, averaging 18°C (65°F) during the day and dropping to a minimum of 3°C (38°F). This winter month sees significantly less precipitation, with only 36 mm (1.4 in) falling over just four days. Despite both months sharing a humidity level of 83%, their overall feel and conditions are markedly different, reflecting the seasonal transition. For more details on January weather, you can check Sanibel weather in January.

September and February offer strikingly different weather experiences. In September, temperatures are warmer, with a minimum of 23°C (74°F) and an average of 28°C (82°F), peaking at 33°C (92°F). The month also sees considerable rainfall, with 169 mm (6.7 in) spread over 20 days, contributing to a high humidity level of 83%. In contrast, February presents a much cooler climate, featuring a minimum temperature of 7°C (45°F) and an average of 21°C (69°F), reaching a maximum of 28°C (83°F). Rainfall is minimal, with only 36 mm (1.4 in) occurring over just 4 days, and humidity remains relatively low at 80%. For more details on the February climate, check out Sanibel weather in February.

September and March present strikingly different weather patterns. September boasts a warm climate with average temperatures ranging from a minimum of 23°C (74°F) to a maximum of 33°C (92°F). It is also quite humid, with an average humidity of 83% and substantial rainfall totaling 169 mm (6.7 in) spread over 20 days. In contrast, March offers a much cooler experience, with average temperatures between a minimum of 9°C (48°F) and a maximum of 28°C (83°F). It features significantly lower precipitation at just 22 mm (0.9 in) over 2 days and a lower humidity level at 75%. For a closer look at March weather specifically, you can check out Sanibel weather in March.

In September, the weather is significantly warmer, with temperatures ranging from a minimum of 23°C (74°F) to a maximum of 33°C (92°F) and an average of 28°C (82°F). This month also sees considerable rainfall, averaging 169 mm (6.7 in) over 20 days, accompanied by high humidity at 83%. In contrast, April features milder temperatures, with a minimum of 13°C (56°F), an average of 24°C (76°F), and a maximum of 31°C (88°F). Precipitation is much lower at 42 mm (1.7 in) over just 7 days, and humidity is also less intense at 68%. For more details on the April climate, check out Sanibel weather in April.

September typically features warmer temperatures compared to May, with minimums of 23°C (74°F) and an average of 28°C (82°F), peaking at 33°C (92°F). In contrast, May has slightly cooler average temperatures, ranging from a minimum of 18°C (65°F) to an average of 26°C (79°F), and a maximum of 32°C (90°F). Additionally, September experiences higher precipitation levels, with 169 mm (6.7 in) over about 20 days, while May sees less rainfall at 122 mm (4.8 in) over just 12 days. Notably, September also has a much higher humidity level at 83%, compared to May's more comfortable 65%. For more details on May weather, visit Sanibel weather in May.

In comparing the weather of September and June, both months feature similar temperature ranges, with a minimum of 23°C (74°F) and a maximum of 33°C (92°F). However, September tends to be slightly warmer on average at 28°C (82°F), while June has an average of 27°C (81°F). Both months experience considerable precipitation, with September receiving 169 mm (6.7 in) over 20 days and June recording 170 mm (6.7 in) over 22 days. Interestingly, September is marked by higher humidity at 83%, compared to June’s more comfortable 73%. For more insights on June's weather patterns, check out Sanibel weather in June.

In comparing September and July weather, both months feature warm temperatures, but September shows slightly cooler averages with a minimum of 23°C (74°F) and a maximum of 33°C (92°F), compared to July's minimum of 24°C (75°F) and maximum of 32°C (90°F). Precipitation is more pronounced in July, with an average of 195 mm (7.7 in) over 26 days, whereas September sees a bit less rain at 169 mm (6.7 in) over 20 days. Additionally, September has a higher humidity level at 83%, while July's humidity is comparatively lower at 77%. For more detailed information, you can check out Sanibel weather in July.

In comparing the weather between September and August, we can see some notable differences. September maintains a similar average temperature of 28°C (82°F) but has a slightly lower minimum temperature of 23°C (74°F) compared to August's 24°C (76°F). Both months experience a maximum temperature of 33°C (92°F), indicating consistent summer heat. However, September is characterized by increased precipitation, totaling 169 mm (6.7 in) over 20 days, which is less than August's 206 mm (8.1 in) across 26 days. Humidity levels are slightly higher in September at 83%, compared to August’s 80%. Overall, while both months are warm and humid, September tends to be a tad wetter. For more details, check out Sanibel weather in August.

September and October showcase a notable transition in weather patterns. September boasts warmer temperatures, with a minimum of 23°C (74°F) and an average of 28°C (82°F), peaking at a maximum of 33°C (92°F). This month is also marked by significant rainfall, accumulating 169 mm (6.7 in) over 20 rainy days, maintaining high humidity levels at 83%. In contrast, October experiences a cooling trend, with a minimum temperature dropping to 14°C (58°F) and an average of 26°C (80°F), while still reaching a maximum of 32°C (90°F). The precipitation decreases substantially to 76 mm (3.0 in) over just 12 days, yet humidity remains constant at 83%. For more detailed information on October conditions, you can check out Sanibel weather in October.

September and November present notable contrasts in weather patterns. September typically features warmer temperatures with minimums around 23°C (74°F) and averages peaking at 28°C (82°F), while November cools down significantly, showcasing minimums dropping to 11°C (52°F) and averages at 23°C (73°F). In terms of precipitation, September is much wetter, experiencing 169 mm (6.7 in) spread over 20 days, compared to November's drier climate with only 44 mm (1.7 in) over just 6 days. Despite the shift in temperature and rainfall, humidity remains consistent at 83% for both months. For a detailed look at the weather in November, check out Sanibel weather in November.

September weather in Sanibel is characterized by warm temperatures, with a minimum of 23°C (74°F) and an average of 28°C (82°F), reaching up to a maximum of 33°C (92°F). This month experiences significant rainfall, totaling 169 mm (6.7 in) over 20 days, along with high humidity at 83%. In contrast, December sees much cooler temperatures, with a minimum of 8°C (46°F) and an average of 20°C (68°F), peaking at 27°C (81°F). Precipitation drops considerably to 52 mm (2.1 in) over just 6 days, while humidity remains similar at 84%. For more detailed information, you can visit Sanibel weather in December.

Compare Sanibel's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Sanibel

As September rolls in, Sanibel's weather becomes notably distinct, with warmer temperatures and a higher likelihood of rain compared to the preceding summer months. The average heat reaches a comfortable yet humid peak, creating a tropical atmosphere that entices those looking for a vibrant escape. With 20 days of precipitation, it's crucial for visitors to embrace the refreshing afternoon showers that are part of the island's charm. Despite the humidity hovering around 83%, the lush surroundings and beautiful landscapes thrive, offering a unique experience in this sun-soaked paradise. For those curious about a more in-depth exploration of Sanibel's climate, check out Sanibel Climate.