Last updated: August 31, 2025
In September, Guaynabo, Puerto Rico, experiences a tropical climate characterized by warm temperatures and significant rainfall. With a maximum temperature reaching 32°C (90°F) and an average of 27°C (81°F), residents can expect warm days complemented by cooler nights that dip to a minimum of 23°C (74°F). This month is also marked by substantial precipitation, totaling 200 mm (7.9 in) spread over approximately 27 days, contributing to the area's lush greenery. With a humidity level averaging 79%, the air feels moist, enhancing the tropical experience of this vibrant region.
In September, Guaynabo, Puerto Rico experiences warm and inviting temperatures, transitioning into the back half of the year. The month showcases a minimum of 23°C (74°F), which is on par with the prevalently warm summer months. With an average temperature of 27°C (81°F), residents and visitors enjoy pleasant conditions for outdoor activities, while the maximum can reach up to 32°C (90°F), highlighting September as a time when the heat starts to peak. As the month unfolds, the temperatures indicate a subtle shift towards cooler fall weather, yet still echo the warmth that makes Puerto Rico a tropical paradise year-round.
In September, Guaynabo, Puerto Rico experiences a notable increase in rainfall, with an impressive 200 mm (7.9 in) of precipitation over the month, marking it as one of the wettest periods of the year. This intense downpour occurs on approximately 27 days, highlighting a trend of frequent but lighter rainfall during this time. As the peak of the rainy season, September transitions from the preceding months, where rainfall steadily rises from 98 mm (3.9 in) in May to a peak in September. Following this peak, precipitation begins to decline in October, demonstrating a seasonal ebbing of moisture after a summer filled with abundant showers. The consistent pattern of increasing rainfall from earlier months, peaking in September, reflects the tropical climate's characteristic rhythm in Guaynabo.
In September, Guaynabo, Puerto Rico experiences a humidity level of 79%, reflecting a slight dip from the more pronounced moisture of 80% during the summer months of July and August. This transitional phase hints at a gradual shift as the region moves into the cooler months, yet the humidity remains relatively high compared to the earlier parts of the year. With levels ranging from 74% in March to 80% in peak summer, it’s clear that Guaynabo maintains a consistently humid climate throughout the year. The overall trend highlights a sustained presence of tropical moisture, making September a month where residents and visitors alike can expect warmth intertwined with the characteristic humidity that defines this beautiful Caribbean locale.
In September, Guaynabo, Puerto Rico experiences a consistently extreme UV Index of 13, maintaining temperatures that demand caution under the sun. With a burn time as brief as 10 minutes, residents and visitors are advised to take precautions, echoing the trends seen throughout the summer months. The UV Index remains in this high range from May through October, highlighting the importance of sun safety during these months. As the year transitions into the milder autumn, the UV Index starts its gradual decline but it’s essential to stay vigilant. For more detailed insights on sun exposure, visit Guaynabo UV Index.
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September in Guaynabo, Puerto Rico, offers a delightful retreat with 313 hours of sunshine, marking a slight dip from the summer peak but remaining vibrant enough to bask in the golden rays. The trend throughout the year shows a steady increase in sunlight from January's 257 hours to May's 356 hours, creating an inviting atmosphere for outdoor activities. While this month’s sunshine hours align with October's, the overall abundance from May to July reflects the region's tropical allure. As the year transitions into autumn, September continues to enchant residents and visitors alike with warm, sunlit days, perfectly capturing the essence of island life.
In Guaynabo, Puerto Rico, September offers a moderate chance of sunny weather, with approximately 44% likelihood of sunshine. This positions the month just above the summer months of July and August, which both see lower probabilities at 38% and 37%, respectively. As the year progresses from the dry months of early winter to late summer, the chances of clear skies fluctuate, peaking in February at 65%. While September's chances are not the highest, they mirror the likelihood found in October, suggesting that the region begins to transition towards more stable weather patterns as it moves into fall. Overall, visitors can expect a fair mix of sun and clouds, making September an appealing time to enjoy the beautiful outdoors.
In Guaynabo, Puerto Rico, September marks a transitional moment in daylight duration, as the summer months begin to wane. With approximately 12 hours of daylight, September shares this amount with the preceding months of March, April, May, and August, highlighting a consistent trend of extended daylight during the warmer seasons. Notably, while daylight peaks at 13 hours during June and July, it then gradually recedes, bringing the daylight hours back in line with the 11-hour days typical of winter months from October through February. This rhythmic pattern reflects the island's tropical climate, where the balance of light and dark shifts gently, allowing residents to savor the lingering warmth of the late summer days.
In Guaynabo, Puerto Rico, the month of September brings a gentle breeze, with an average wind speed of just 2.4 m/s (5 mph)—the lowest of the year. This tranquil shift follows the peak wind speeds of the summer months, which range between 3.5 to 4.0 m/s (8 to 9 mph), creating a pleasant and calming atmosphere as summer transitions into fall. As the year progresses, winds begin to pick up again in October, averaging 2.6 m/s (6 mph), suggesting a slow return to the more robust breezes characteristic of the preceding months. Overall, September offers a serene reprieve, inviting residents and visitors alike to enjoy the peaceful surroundings as the tropical landscape begins to change.
Weather in Guaynabo varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Guaynabo, focusing on differences in temperature, rainfall, humidity, and UV levels.
In September, the weather is warm and humid, with average temperatures ranging from a minimum of 23°C (74°F) to a maximum of 32°C (90°F). The month is characterized by significant rainfall, with a total precipitation of 200 mm (7.9 in) spread over 27 days, resulting in a high humidity level of 79%. In contrast, January sees milder conditions with average temperatures ranging from a minimum of 19°C (66°F) to a maximum of 29°C (84°F). Precipitation drops considerably to 48 mm (1.9 in) across 16 days, and humidity remains moderately lower at 76%. For more specifics on January weather, you can check Guaynabo weather in January.
In comparing the weather conditions of September and February, September tends to be hotter and wetter. With average temperatures reaching 27°C (81°F) and highs of 32°C (90°F), September displays a more tropical feel, contrasted by February's milder average of 24°C (75°F) and maximum of 28°C (83°F). Rainfall is significantly higher in September, accumulating 200 mm (7.9 in) over 27 days, while February sees a much lighter 53 mm (2.1 in) across just 18 days. Humidity slightly decreases from 79% in September to 75% in February, contributing to a more comfortable atmosphere during the latter month. For more detailed insights, check out Guaynabo weather in February.
In comparing the weather of September and March, September tends to be warmer and more humid, with average temperatures ranging from a minimum of 23°C (74°F) to a maximum of 32°C (90°F). The month experiences significant rainfall, totaling 200 mm (7.9 in) over 27 days, resulting in a humidity level of 79%. On the other hand, March features slightly cooler temperatures, with averages from a minimum of 20°C (69°F) to a maximum of 29°C (85°F), and much less precipitation at 80 mm (3.2 in) over 21 days, accompanied by a humidity level of 74%. For more detailed insights into March weather, visit Guaynabo weather in March.
When comparing the weather in September and April, it's evident that September tends to be warmer and wetter. In September, temperatures range from a minimum of 23°C (74°F) to a maximum of 32°C (90°F), with an average of 27°C (81°F). In contrast, April has slightly cooler temperatures, with a minimum of 21°C (70°F) and a maximum of 30°C (86°F), averaging around 25°C (77°F). Additionally, September experiences considerably higher precipitation, with 200 mm (7.9 in) spread over 27 days, compared to April's 77 mm (3.0 in) over just 20 days. Humidity levels are also slightly higher in September at 79%, as opposed to April's 75%. For more details on April weather, you can check Guaynabo weather in April.
September and May offer distinct weather experiences, with September generally warmer and wetter. In September, the temperatures range from a minimum of 23°C (74°F) to a maximum of 32°C (90°F), accompanied by high humidity at 79% and significant rainfall totaling 200 mm (7.9 in) over 27 days. In contrast, May features slightly cooler temperatures, with a minimum of 22°C (72°F) and a maximum of 31°C (87°F), along with lower precipitation levels of 98 mm (3.9 in) across 24 days and a humidity of 75%. For a deeper look at May's climate specifics, visit Guaynabo weather in May.
When comparing the weather in September and June, we observe a few key similarities and differences. Both months have a minimum temperature of around 23°C (74°F) and an average temperature near 27°C (81°F), but September tends to be slightly warmer with a maximum temperature of 32°C (90°F) compared to June's 31°C (88°F). Additionally, September experiences significantly more precipitation, with 200 mm (7.9 in) spread over 27 days, whereas June has only 99 mm (3.9 in) over 23 days. Humidity levels are quite comparable, with September at 79% and June slightly lower at 77%. For detailed information on June weather, you can check out Guaynabo weather in June.
In comparing the weather of September and July, both months exhibit similar temperature ranges, with minimum temperatures around 23°C (74°F) and average highs hovering near 27°C (81°F). However, September sees slightly warmer maximum temperatures reaching up to 32°C (90°F), compared to July's maximum of 31°C (88°F). Precipitation is notably higher in September, totaling 200 mm (7.9 in) over 27 days, while July experiences significantly less rainfall at 124 mm (4.9 in) across 24 days. Humidity levels are also comparable, with September at 79% and July at 80%, indicating a persistently humid climate during both months. For more specific details, you can check Guaynabo weather in July.
In comparing the weather between September and August, we see some notable similarities and differences. Both months experience warm temperatures, with September having a slightly higher maximum of 32°C (90°F) compared to August's 31°C (89°F). The average temperature remains consistent at 27°C (81°F) for both months. However, September is considerably wetter, receiving 200 mm (7.9 in) of precipitation over 27 days, while August sees only 130 mm (5.1 in) over 25 days. Humidity levels are similar, with September at 79% and August at 80%. For more detailed information, you can check Guaynabo weather in August.
September and October exhibit similar temperature patterns, with both months experiencing a minimum of 23°C (74°F) and an average of 27°C (81°F). However, October shows a slight decrease in maximum temperature, peaking at 31°C (88°F) compared to September's 32°C (90°F). Additionally, October tends to be slightly drier, recording 183 mm (7.2 in) of precipitation compared to September's 200 mm (7.9 in), although both months share an equal number of rainy days at 27. Humidity levels remain consistent, with October being marginally lower at 78%, compared to September's 79%. For more details, you can check out Guaynabo weather in October.
September and November in Guaynabo exhibit notable differences in weather patterns. September is warmer with a minimum temperature of 23°C (74°F) and an average of 27°C (81°F), peaking at a high of 32°C (90°F). It also experiences higher rainfall, accumulating 200 mm (7.9 in) over 27 days with a humidity level of 79%. In contrast, November brings slightly cooler temperatures, with a minimum of 22°C (72°F) and an average of 26°C (79°F), reaching a maximum of 30°C (86°F). Precipitation decreases to 120 mm (4.7 in) over 23 days, accompanied by a similar humidity level of 78%. For more detailed insights, you can explore Guaynabo weather in November.
When comparing the weather in September to that of December, noticeable differences emerge. September experiences warmer temperatures, with an average of 27°C (81°F) and highs reaching up to 32°C (90°F), while December sees slightly cooler averages at 25°C (77°F) and maximum temperatures of 30°C (86°F). September is also marked by significantly higher precipitation, totaling 200 mm (7.9 in) across 27 days, compared to December's more moderate 66 mm (2.6 in) over 22 days. Humidity remains fairly consistent between the two months, with September at 79% and December slightly lower at 76%. For more detailed information on the weather during this month, visit Guaynabo weather in December.
As September rolls into Guaynabo, the weather exhibits a distinct personality compared to other months. With average temperatures hovering around a warm 27°C (81°F), the high humidity levels of 79% can make the air feel particularly sultry. Unlike the drier months, September is characterized by frequent rain, accumulating nearly 200 mm (7.9 in) over the course of about 27 days, contributing to a lush, vibrant landscape. While sunshine still makes its appearance, the increased precipitation often leads to brief, refreshing downpours that can cool the atmosphere temporarily. For those keen on understanding how these weather patterns contribute to Guaynabo's unique charm, more insights can be found at Guaynabo Climate.