Last updated: February 24, 2025
Experience the vibrant weather of Key Largo, United States in September, where the average temperature hovers around a warm 28°C (83°F), perfect for outdoor adventures. With daily highs reaching up to 30°C (87°F) and comfortable lows of 25°C (77°F), the climate invites relaxation and exploration. However, be prepared for moisture-laden days; September sees a significant precipitation amount of 179 mm (7.1 in) spread over 18 days, resulting in a humidity level of 76%. Whether you’re diving into the crystal-clear waters or strolling along the sun-kissed coast, September’s weather in Key Largo promises a blend of warmth and occasional refreshing showers.
In September, Key Largo maintains its tropical charm with warm temperatures that reflect the summer's lingering embrace. The month starts off with a minimum of 25°C (77°F) and reaches an average of 28°C (83°F), peaking at around 30°C (87°F). This stability in warmth follows a pattern established over the preceding months, where temperatures consistently hover in the high 20s. September's weather is characterized by its balmy atmosphere, perfect for enjoying the island's stunning beaches and vibrant marine life. As the month progresses, temperatures will begin to cool slightly, hinting at the approaching autumn, yet for now, Key Largo remains a paradise defined by sun-soaked days and inviting ocean breezes.
In September, Key Largo experiences a significant uptick in precipitation, with an impressive 179 mm (7.1 in) recorded, marking it as the wettest month of the year. This spike aligns with the tropical climate of the region, where rainfall days average around 18 during this month, reflecting the frequent afternoon showers common to late summer. Comparatively, May also shows high precipitation levels at 155 mm (6.1 in), but September stands out not only for its volume but also for continuing the trend of increased rainfall seen throughout the summer months. As the season transitions into fall, Key Largo's lush landscape thrives, showcasing nature's vibrancy fueled by the abundant rainfall.
In September, Key Largo experiences a humidity level of 76%, marking a notable increase from the drier months of late spring and early summer. As the summer heat reaches its peak, humidity levels rise slightly compared to the preceding months—culminating in a trend that sees the island's air becoming more saturated. This pattern is typical as the season transitions toward autumn, with September acting as a bridge between the warmth of summer and the arrival of the wetter fall months. Interestingly, humidity remains consistent in the subsequent months, reflecting a slight uptick in moisture as the year draws to a close. Overall, September’s humidity is a reminder of the tropical climate's inherent warmth and moisture, setting the stage for the lush, vibrant beauty that characterizes this enchanting locale.
In September, Key Largo experiences an extreme UV Index of 12, maintaining the high levels seen throughout the summer months. With a burn time of just 10 minutes, skin protection becomes paramount as the sun’s intensity remains fierce. This trend of elevated UV exposure began in the early spring, peaking during the sultry summer months, and shows remarkable consistency as it transitions into fall. Visitors should be vigilant, applying sunscreen regularly and seeking shade whenever possible to safeguard against harmful rays. For those planning their time in the sun, staying informed through reliable resources is crucial—check out the local details at Key Largo UV Index.
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As summer gracefully transitions into autumn, September in Key Largo maintains a delightful glow, boasting 317 hours of sunshine. While the days grow shorter, the warm embrace of sunlight lingers, reflecting a trend of consistent brightness from the busy summer months of July and August. These peak months, rich in sunshine with 347 and 342 hours respectively, set a vibrant tone for September. As the sun dips into the horizon earlier each evening, visitors can still enjoy the tail-end of summer's radiance, making this coastal paradise an inviting escape as it shifts towards the milder days of October. Overall, September’s sun-kissed days serve as a gentle reminder of the warmth lingering in the tropics before the cooler months arrive.
In Key Largo, September tends to feature a 34% chance of sunny weather, positioning it as one of the less favorable months for sun seekers. This trend marks a notable dip compared to the preceding summer months, where July and August present even lower probabilities of sunshine at 26% and 28%, respectively. After a peak in sunny days during the winter and early spring months—most notably February's impressive 67%—the likelihood of sun gradually decreases as the year progresses. As October rolls in, the chances improve to 50%, highlighting the fluctuation in weather patterns in this beautiful locale. Overall, while September may not boast the best odds for basking in sunshine, it still offers a glimpse of warmth amid the fading summer season.
In Key Largo, the daylight duration in September marks a subtle transition as summer begins to wane. With 12 hours of daylight, September mirrors the longer days of August but hints at the upcoming shift into autumn. This month is part of a gradual decrease from the peak daylight hours observed in the early summer months of June, July, and August, which enjoyed a consistent 13 hours. Looking ahead, the days will continue to shorten, with October witnessing a decline to 11 hours, reflecting the natural rhythm of the seasons. As such, September serves as a delightful bridge, allowing residents and visitors alike to relish those ample sunny hours before the light begins to fade.
In Key Largo, September brings a noticeable dip in wind speed, averaging 3.2 m/s (7 mph), making it the calmest month of the year. This gentle breeze contrasts sharply with earlier months, where wind speeds hover around 5.0 to 6.4 m/s (11 to 14 mph) from January through August. The trend indicates a gradual decrease in wind strength as summer transitions into early autumn, providing a serene atmosphere perfect for relaxing by the water or enjoying leisurely activities. As the season shifts towards October, wind speeds begin to pick up again, returning to an average of 5.0 m/s (11 mph), signaling the return of livelier breezes to this picturesque destination.
The weather in Key Largo 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 Key Largo and find detailed weather information for every month.
September and January present a stark contrast in weather patterns. In September, temperatures typically range from a minimum of 25°C (77°F) to a maximum of 30°C (87°F), with an average of about 28°C (83°F). This month is also characterized by high humidity at 76% and significant precipitation, totaling 179 mm (7.1 in) over 18 days. In comparison, January offers a cooler climate, with temperatures ranging from a minimum of 10°C (50°F) to a maximum of 26°C (80°F) and an average of 22°C (71°F). Precipitation is considerably lower in January, averaging only 31 mm (1.2 in) over just 6 days, and humidity increases slightly to 81%. For more detailed insights into January weather, visit Key Largo weather in January.
September and February showcase contrasting weather patterns. September is significantly warmer, with average temperatures ranging from a minimum of 25°C (77°F) to a maximum of 30°C (87°F), accompanied by substantial precipitation of 179 mm (7.1 in) over 18 days. In contrast, February presents a cooler climate with temperatures averaging between 14°C (57°F) and 26°C (80°F) and much lower precipitation at 35 mm (1.4 in) over just 7 days. Despite February's reduced rainfall, humidity remains relatively high at 79%, similar to the 76% experienced in September. For more details, check out Key Largo weather in February.
September and March exhibit contrasting weather patterns. September boasts warmer temperatures with a minimum of 25°C (77°F) and an average of 28°C (83°F), peaking at 30°C (87°F). However, it is also characterized by high precipitation, with 179 mm (7.1 in) of rain over 18 days, leading to consistent humidity levels of 76%. In comparison, March offers a cooler climate with minimum temperatures of 15°C (59°F) and an average of 23°C (74°F), reaching a maximum of 26°C (80°F). Precipitation in March is significantly lower at 27 mm (1.0 in) over just 4 days, maintaining the same humidity level of 76%. For more detailed information, you can visit Key Largo weather in March.
In comparing the weather of September and April, we see notable differences in temperature and precipitation. September tends to be warmer, with average temperatures reaching 28°C (83°F) and maximums hitting 30°C (87°F), compared to April's average of 25°C (77°F) and maximum of 28°C (83°F). Additionally, September experiences significantly higher precipitation, with 179 mm (7.1 in) falling over 18 days, while April sees only 47 mm (1.8 in) across 9 days. Humidity levels are fairly similar, with September at 76% and April at 73%. To explore more about April weather specifically, you can visit Key Largo weather in April.
September tends to be warmer and more humid than May, with average temperatures around 28°C (83°F) compared to May's 26°C (79°F). While September sees higher maximum temperatures of 30°C (87°F) versus May's 29°C (84°F), it also experiences significantly more rainfall, averaging 179 mm (7.1 in) over 18 days compared to May's 155 mm (6.1 in) across 13 days. This increased precipitation and humidity in September, at 76%, contrasts with May's lower humidity of 71%. For more detailed insights into the weather during this period, you can explore Key Largo weather in May.
In comparing the weather of September and June, we find that both months enjoy warm temperatures with similar maximums reaching up to 30°C (87°F). September, however, tends to be slightly warmer on average at 28°C (83°F) compared to June's average of 27°C (82°F). While the minimum temperatures are close, with September starting at 25°C (77°F) and June at 24°C (75°F), September experiences significantly more precipitation, with 179 mm (7.1 in) compared to June's 112 mm (4.4 in) over the same number of rainy days—18 in total. Additionally, humidity is higher in September at 76%, compared to June's 69%. For more detailed information on June weather, you can check Key Largo weather in June.
In comparing the weather between September and July, both months exhibit warm temperatures, with September having a slightly lower maximum temperature of 30°C (87°F) compared to July’s 31°C (87°F). Both months have a minimum temperature of about 25°C (77°F), and their average temperatures remain at a comfortable 28°C (83°F). However, September tends to be wetter, receiving 179 mm (7.1 in) of precipitation over 18 days, while July sees only 103 mm (4.1 in) over 17 days. Additionally, September has a higher average humidity of 76%, compared to July's 70%. For more detailed weather information, check out Key Largo weather in July.
In comparing the weather of September to August, we see that both months share similar temperature ranges, with minimums at 25°C (77°F), averages at 28°C (83°F), and maximums at 30°C (87°F). However, September experiences significantly higher precipitation with 179 mm (7.1 in) compared to August's 108 mm (4.3 in), and while both months have rain on 18 days, the humidity in September is slightly elevated at 76% versus August's 72%. For more detailed insights on August conditions, you can visit Key Largo weather in August.
In September, the weather is characterized by warmer temperatures, with a minimum of 25°C (77°F) and an average high reaching 30°C (87°F). The month also sees substantial rainfall, totaling 179 mm (7.1 in) over 18 days, paired with a humidity level of 76%. In contrast, October brings cooler temperatures, with a minimum of 18°C (65°F) and an average high of 29°C (85°F). Although October experiences slightly less precipitation at 142 mm (5.6 in) over the same number of rainy days, humidity rises slightly to 79%. For more detailed information, you can visit Key Largo weather in October.
In September, the weather is notably warmer with temperatures ranging from a minimum of 25°C (77°F) to a maximum of 30°C (87°F) and an average of 28°C (83°F). This month also experiences significant rainfall, with 179 mm (7.1 in) spread over 18 days, contributing to a humidity level of 76%. In contrast, November brings a cooler climate, with minimum temperatures dropping to 15°C (60°F) and average temperatures settling at 25°C (77°F). The rainfall is considerably less in November, totaling 82 mm (3.2 in) over 11 days, accompanied by a slight increase in humidity to 80%. For a more detailed look at the weather in November, check out Key Largo weather in November.
In September, temperatures in Key Largo are notably warmer, with average highs reaching 30°C (87°F) and humidity levels around 76%. The month is also characterized by significant rainfall, totaling 179 mm (7.1 in) over 18 days, creating a humid and tropical atmosphere. In contrast, December brings cooler temperatures, with average highs of 27°C (80°F) and a much lower rainfall of just 44 mm (1.7 in) across 8 days, while humidity rises slightly to 81%. This shift makes December a more pleasant time for outdoor activities compared to the wetter and warmer September. For more information, check out Key Largo weather in December.
As September rolls into Key Largo, the weather takes on a distinctive character, blending warmth and humidity with increased rainfall. While temperatures remain comfortably warm, with average highs around 28°C (83°F), the month sees a noticeable rise in precipitation compared to the summer months, marked by approximately 18 rainy days and a total of 179 mm (7.1 in) of rain. This spike in humidity, averaging 76%, fosters a lush, tropical atmosphere, making the landscape vibrantly alive. Despite the rainy spells, those visiting in September can still enjoy the beautiful waters and rich wildlife that Key Largo is known for. For more detailed insights on what to expect throughout the year, check out Key Largo Climate.