Last updated: February 24, 2025
In September, Key West experiences warm temperatures that delight visitors, with a maximum reaching 30°C (86°F) and an average of 28°C (83°F). The nights are comfortably mild, with minimum temperatures around 25°C (77°F). While the month sees significant precipitation, totaling 172 mm (6.8 in) over approximately 17 days, this moisture contributes to the lush tropical environment. With an average humidity level of 76%, the atmosphere is rich and vibrant, making September a unique time to explore the charm of this island paradise.
In September, Key West embraces the lingering warmth of summer, with temperatures averaging a balmy 28°C (83°F). Nighttime lows hover around 25°C (77°F), ensuring that evenings remain comfortably tropical. As the month progresses, the daytime highs reach up to 30°C (86°F), reflecting a slight dip from the peak summer heat of August, yet still inviting for beachgoers and outdoor enthusiasts. This pattern illustrates a gradual transition toward autumn while still basking in the vibrant, warm weather that characterizes this enchanting island. Overall, September presents a delightful blend of warmth and comfort, making it an appealing time to experience Key West's tropical allure.
September marks a significant turning point in Key West's precipitation patterns, emerging as the rainiest month of the year with an average of 172 mm (6.8 in), spanning 17 days of rainfall. This surge in precipitation transitions from the relatively moderate summer months, where July and August deliver 103 mm (4.0 in) and 100 mm (3.9 in) respectively. As summer gives way to fall, the frequency and intensity of rain indicates the onset of tropical storms and hurricanes, making it a critical time for both residents and visitors. Following September, October also remains wet but sees a reduction to 133 mm (5.2 in) over 18 days, suggesting a gradual tapering of the rainy season. Overall, September is not just a peak in rainfall; it’s a vivid reminder of the dynamic weather patterns that characterize this vibrant coastal region.
In September, Key West experiences an average humidity of 76%, marking a slight increase from the summer months. Following the trend of gradual decline from a peak of 81% in January to a low of 69% in June, humidity levels begin to rise again as autumn approaches. This is characteristic of the seasonal shift, where humidity stabilizes slightly higher in September than in the preceding months of July and August, which sit at 70% and 72% respectively. As the year progresses towards October, humidity levels are poised to increase further, reminding residents and visitors alike that tropical conditions linger in this charming destination.
In September, Key West experiences a UV Index of 11, categorized as extreme, with a burn time of just 10 minutes. This trend continues the pattern established from June through August, where the UV Index consistently hovered at its peak levels of 12 or higher. With summer's intensity fading slightly, September still demands caution and protection from the sun, as the risks remain significant. This month’s UV levels are slightly reduced from the summer’s peak, yet still remind us to be vigilant in sun safety. For more detailed insights, check out Key West UV Index.
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As summer gently fades into autumn, September in Key West continues to bask in the warmth of sunshine, boasting 320 hours of glorious daylight. This month marks a gradual decline from the sun-soaked highs of July and August, which saw an impressive 351 and 340 hours respectively. However, September still shines brighter than the earlier months of the year, such as January with only 228 hours. Trends reveal that Key West enjoys an abundance of sunshine throughout the year, but the late summer and early fall months remain particularly radiant, inviting visitors to indulge in outdoor adventures before the cooler autumn days set in.
In Key West, the weather in September tends to be quite variable, with only a 36% chance of sunny days. This marks a noticeable dip compared to the sunniest months of the year, like March and February, which boast chances of sunshine at 72% and 68% respectively. The summer months, notably June and July, also show a decline in sunny weather, hinting at a seasonal trend that leads into September's lower probabilities. As autumn approaches, residents and visitors alike may find themselves hoping for clearer skies amidst the remnants of summer's heat and increase in rain. While September isn't the sunniest time to visit, the allure of Key West's charm and vibrant atmosphere can still shine through its occasional clouds.
As summer fades in Key West, September brings a delightful 12 hours of daylight, mirroring the longer days of August. This month marks a gentle transition from the peak sunlight of summer, where daylight consistently stretched to 13 hours. With each passing day in September, the sunlight subtly diminishes, signaling the approach of fall, yet still invites ample opportunity for outdoor adventures. As the days gradually shorten, the vibrant spirit of the island thrives, ensuring visitors can enjoy a perfect blend of sun-soaked days and enchanting twilight evenings.
As September settles in Key West, the wind begins to whisper softly, with average speeds dipping to 3.6 m/s (8 mph). This marks the year's most tranquil month, nearly half as breezy as the peak wind times in March and April, when gusts reach around 6.8 m/s (15 mph). The gentle breezes of September provide a stark contrast to the summer's heat, offering a serene backdrop for beachgoers and adventurers alike. After a peak in late spring and early summer, the overall trend shows a gradual decline in wind speed as the year progresses into autumn, setting the stage for the cooler, more refreshing breezes of October that follow. In this paradise, September’s calm winds invite relaxation, perfectly pairing with the island's vibrant sunsets.
The weather in Key West 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 West and find detailed weather information for every month.
In September, the weather is significantly warmer, with average temperatures reaching around 28°C (83°F) and maximums peaking at 30°C (86°F). This month also experiences considerable rainfall, with about 172 mm (6.8 in) falling over 17 days, contributing to high humidity levels of 76%. In contrast, January offers a much cooler experience, with average temperatures of 22°C (71°F) and maximums at 26°C (79°F). Precipitation drops dramatically to 27 mm (1.1 in) over just 5 days, while humidity remains slightly higher at 81%. For more details on specific conditions, you can check out Key West weather in January.
In comparing September and February weather, September is distinctly warmer, with temperatures ranging from a minimum of 25°C (77°F) to an average of 28°C (83°F) and a maximum of 30°C (86°F). It also experiences significantly higher precipitation, with 172 mm (6.8 in) spread over 17 days, resulting in a humid environment at 76% humidity. In contrast, February sees milder temperatures with a minimum of 14°C (58°F), an average of 23°C (74°F), and a maximum of 26°C (80°F). The month is much drier, receiving only 27 mm (1.1 in) of rain over just 4 days, along with slightly increased humidity at 79%. For more detailed information on February weather in Key West, you can check out Key West weather in February.
When comparing the weather in September and March, it's clear that September is significantly warmer and wetter. September features a minimum temperature of 25°C (77°F) and an average high of 30°C (86°F), while March offers cooler temperatures, with a minimum of 17°C (62°F) and a maximum of 26°C (80°F). Additionally, September experiences considerable rainfall, with 172 mm (6.8 in) over 17 days, compared to March's mild precipitation of just 18 mm (0.7 in) across 4 days. Both months share the same humidity level of 76%, but the overall climate in September tends to feel more oppressive due to the increased heat and moisture. For more details on March weather, you can check Key West weather in March.
September and April present contrasting weather patterns. In September, temperatures are warmer, with a minimum of 25°C (77°F) and averaging around 28°C (83°F), reaching a maximum of 30°C (86°F). This month also experiences significantly higher precipitation, with 172 mm (6.8 in) over 17 days, contributing to a high humidity of 76%. In contrast, April enjoys milder conditions, with a minimum temperature of 19°C (67°F) and an average of 25°C (77°F), peaking at 29°C (84°F). The precipitation in April is considerably lower at 40 mm (1.6 in) over just 7 days, resulting in a slightly drier atmosphere with 73% humidity. For more detailed information, check out Key West weather in April.
In comparing the weather between September and May, it is evident that September tends to be slightly warmer and wetter. September boasts minimum temperatures of around 25°C (77°F) and averages around 28°C (83°F), with maximums reaching 30°C (86°F). In contrast, May experiences a bit cooler temperatures, with minimums at 22°C (72°F) and average highs of 29°C (84°F). Additionally, September sees significantly more precipitation, with 172 mm (6.8 in) over approximately 17 days, compared to May's 139 mm (5.5 in) across only 11 days. The humidity is also higher in September at 76%, while May presents a more comfortable 71%. For a detailed look at May's weather, you can visit Key West weather in May.
In comparing the weather between September and June, both months exhibit similar average temperatures, with September having a minimum of 25°C (77°F) and June slightly cooler at 24°C (76°F). However, both months peak at around 30°C (86°F for September and 87°F for June), highlighting consistent warmth throughout. A significant difference lies in precipitation; September experiences a much wetter climate with 172 mm (6.8 in) over 17 days, compared to June’s 94 mm (3.7 in) across 14 days. Additionally, September has higher humidity levels at 76%, while June's humidity is more moderate at 69%. For more detailed information about the weather in June, you can visit Key West weather in June.
In comparison to July, September experiences slightly more consistent temperatures, with minimums around 25°C (77°F) and maximums reaching 30°C (86°F) compared to July’s maximum of 30°C (87°F). Both months have an average temperature of 28°C (83°F); however, September is noticeably wetter, receiving 172 mm (6.8 in) of precipitation over 17 days, while July sees only 103 mm (4.0 in) across 15 days. Additionally, September's higher humidity level of 76% contrasts with July's 70%, making it feel a bit more muggy. For a detailed look at July's weather specifics, you can check out Key West weather in July.
In comparing the weather between August and September, we observe that September maintains a similar temperature range, with a minimum of 25°C (77°F) and a maximum of 30°C (86°F), similar to August's figures. However, September experiences slightly cooler average temperatures at 28°C (83°F) compared to August's 29°C (84°F). Notably, September is characterized by significantly higher precipitation, totaling 172 mm (6.8 in) over 17 days, compared to August's 100 mm (3.9 in) over 15 days. Additionally, September also has a higher humidity level at 76%, compared to August’s 72%. For a more detailed look at the weather conditions during this period, check out Key West weather in August.
In September, the weather tends to be warmer with a minimum temperature of 25°C (77°F) and an average of 28°C (83°F), peaking at around 30°C (86°F). This month is also characterized by higher precipitation, measuring 172 mm (6.8 in) over 17 days, along with a humidity level of 76%. Conversely, October sees slightly cooler temperatures, with a minimum of 20°C (69°F) and an average of 27°C (81°F), reaching up to 29°C (85°F). Precipitation decreases to 133 mm (5.2 in) across 18 days, and humidity rises slightly to 79%. Overall, October provides a transition towards more comfortable weather. For more specific details about this month, check out Key West weather in October.
In September, the weather tends to be warmer, with average temperatures reaching 28°C (83°F) and maximums peaking at 30°C (86°F), alongside substantial rainfall totaling 172 mm (6.8 in) over 17 days. In contrast, November experiences cooler temperatures, with an average of 25°C (77°F) and a maximum of 28°C (83°F). Precipitation also decreases significantly in November to 83 mm (3.3 in) over just 10 days, while humidity remains relatively high at 80%. This shift makes November a more pleasant time to enjoy outdoor activities, in comparison to the often humid and rainy September. For more detailed insights, you can visit Key West weather in November.
In September, the weather is noticeably warmer, with average temperatures hovering around 28°C (83°F) and maximums reaching up to 30°C (86°F). This month also experiences significant rainfall, with 172 mm (6.8 in) of precipitation spread over 17 days, contributing to a high humidity level of 76%. In contrast, December brings cooler temperatures, with an average of 23°C (74°F), and maximums around 27°C (80°F), while the rainfall dramatically decreases to just 44 mm (1.7 in) over only 5 days. The humidity also rises slightly to 81%. For a more detailed look at what to expect, you can visit Key West weather in December.
September in Key West brings a unique blend of warmth and moisture, distinguishing it from the drier, more temperate months of the year. With average temperatures hovering around a comfortable 28°C (83°F), the season offers a tropical feel but is accompanied by a higher humidity level of 76%. Rainfall makes its presence known, with roughly 172 mm (6.8 in) spread across 17 days, hinting at the end of the wet season while maintaining the lushness that defines this stunning destination. Those planning a visit will find that September’s weather, while slightly more unpredictable, adds a layer of vibrancy to the Key West experience. To learn more about the climate and seasonal changes, check out Key West Climate.