Last updated: August 21, 2025
In September, San Ramon, Costa Rica, experiences a tropical climate characterized by warm temperatures and high humidity. The maximum temperature reaches around 29°C (85°F), while the average settles at a comfortable 23°C (74°F), dipping to a cool 18°C (66°F) at night. This month is marked by substantial precipitation, with an impressive total of 461 mm (18.2 in) over approximately 29 days, creating a lush and vibrant landscape. With humidity levels averaging 81%, visitors can expect a warm, wet ambiance that enhances the region's natural beauty.
In September, San Ramon, Costa Rica, experiences a tranquil climate that marks the transition into the rainy season. Temperatures are mild, with minimums around 18°C (66°F) and maximums peaking at 29°C (85°F). The average temperature settles at a comfortable 23°C (74°F), similar to the previous months. This consistency reflects a pleasing warmth throughout the day, making it ideal for those looking to explore the lush landscapes, albeit with a chance of afternoon showers. As the month progresses, the region's vibrant greenery flourishes, offering breathtaking views and a rejuvenating atmosphere, perfect for nature enthusiasts.
September marks a pivotal point in San Ramon's rainy season, showcasing a significant surge in precipitation with 461 mm (18.2 in) of rainfall, making it one of the wettest months of the year. This deluge, occurring over 29 days, continues the trend established throughout the preceding months, where the skies have opened up with intense showers. Following the heavy downpours of August, which received 393 mm (15.5 in), September escalates the wet conditions, setting the stage for October, which is expected to eclipse these numbers with 639 mm (25.2 in). This consistent and robust rainfall not only defines the region’s lush landscapes but also illustrates the persistent nature of its tropical climate, making it a defining feature of life in San Ramon during this time.
In September, San Ramon, Costa Rica experiences a notable humidity level of 81%, which is slightly lower than the peak months of June and July, where humidity soars to 84% and 85%, respectively. The overall trend shows a gradual increase in humidity from the beginning of the year, starting at 68% in January and reaching its zenith during the rainy season in the mid-year months. Following September, humidity begins to taper off as the year winds down, dropping to 80% in both October and November. This consistent pattern underscores the tropical climate's characteristic humidity fluctuations, making September a prime time to experience the lush landscapes that thrive in such moisture-laden air.
In September, San Ramon, Costa Rica, continues to experience an extreme UV Index of 13, maintaining the high levels seen throughout the previous months. This pattern, characterized by a consistent burn time of just 10 minutes, emphasizes the need for protection against the sun's intense rays. From January to September, it's clear that the region remains under extreme exposure conditions, with UV Index values frequently peaking between 12 and 15. As the year progresses into October, the UV Index remains elevated at 14, suggesting that while there may be slight fluctuations, sun protection is crucial for outdoor activities year-round. For a comprehensive overview, you can find more details at San Ramon UV Index.
UV Risk Categories
September in San Ramon, Costa Rica, brings a delightful 230 hours of sunshine, a gentle dip compared to the peak sunny months during the first half of the year. Following the bright and vibrant days of March, which boasts an impressive 329 hours, the weather gradually transitions, yet September still offers ample daylight to enjoy the lush landscapes. As the region prepares for October and November, which average around 211 and 229 hours respectively, those visiting in September can bask in a comfortable balance of sunshine and the beginnings of the lush rainy season, making it a perfect time for exploration and relaxation in this paradise.
In September, the likelihood of sunny weather in San Ramon, Costa Rica, is notably low, with only a 10% chance of sunshine. This trend reflects a broader pattern as the region transitions from the dry season into the rainy months. From January through April, sunny days are more frequent, peaking at 57% in January. However, as temperatures rise and the rainy season sets in, the chances for clear skies plummet, reaching their annual low in September before slowly increasing again in November. Therefore, if you’re planning a visit during this month, be prepared for the increased possibility of rain rather than basking in the sun.
In San Ramon, Costa Rica, the month of September continues the trend of consistent daylight, offering an enjoyable 12 hours each day. This pattern reflects a stable tropical climate where daylight duration remains largely unchanged across the year, with a notable equilibrium in the summer months from March to August and September. As the year progresses toward October, daylight begins to taper off to 11 hours, signaling the gradual approach of shorter days. This rhythmic cycle of light enhances the vibrant ecosystem of the region, making September an inviting time to explore the lush landscapes bathed in abundant daylight.
As summer transitions into fall, September's wind in San Ramón, Costa Rica, offers a gentle breath of air, averaging just 1.2 m/s (3 mph). This subtle breeze continues the trend of decreasing wind speeds seen since the height of summer, peaking at 2.1 m/s (5 mph) in March and gradually tapering off through the months. By September, the atmosphere is serene, allowing locals and visitors alike to embrace the mellow pace of life. The wind whispers past, inviting moments of reflection and enjoyment of the lush surroundings, as nature seamlessly shifts towards the relaxed vibes of the rainy season.
Weather in San Ramon varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in San Ramon, focusing on differences in temperature, rainfall, humidity, and UV levels.
In comparing the weather between September and January, both months display an average temperature of 23°C (74°F), but their overall conditions diverge significantly. September experiences warmer highs of up to 29°C (85°F) and is marked by high humidity at 81%, along with frequent rainfall totaling 461 mm (18.2 in) over 29 days. In contrast, January offers a slightly cooler maximum of 31°C (87°F) but with much less humidity at 68% and significantly lower precipitation levels of only 28 mm (1.1 in) spread over just 7 days. For more detailed insights on January weather, visit San Ramon weather in January.
When comparing the weather in September and February, it's clear that September tends to be much wetter and more humid. With average temperatures ranging from a minimum of 18°C (66°F) to a maximum of 29°C (85°F) and 461 mm (18.2 in) of precipitation over 29 days, September is characterized by frequent rain and high humidity levels at 81%. In contrast, February offers a drier and warmer climate, with temperatures ranging from a minimum of 16°C (62°F) to a maximum of 31°C (88°F) and only 13 mm (0.5 in) of rainfall spread over just 3 days, resulting in a lower humidity of 68%. For a detailed look at February weather, check out San Ramon weather in February.
September and March present contrasting weather patterns. In September, temperatures range from a minimum of 18°C (66°F) to a maximum of 29°C (85°F), with an average of 23°C (74°F). This month experiences significant rainfall, totaling 461 mm (18.2 in) over 29 days, leading to high humidity levels of 81%. In stark contrast, March boasts higher average temperatures, with a minimum of 18°C (64°F) and a maximum of 32°C (89°F), averaging 25°C (77°F). Precipitation is minimal during this month, amounting to only 18 mm (0.7 in) across just 4 days, and humidity drops to a more comfortable 66%. For a detailed look at March weather in San Ramon, you can visit San Ramon weather in March.
September and April showcase contrasting weather patterns, particularly in terms of temperature and precipitation. In September, temperatures range from a minimum of 18°C (66°F) to a maximum of 29°C (85°F), with an average of 23°C (74°F). This month is characterized by high humidity at 81% and significant rainfall, totaling 461 mm (18.2 in) over 29 days. In contrast, April enjoys slightly warmer temperatures, with a minimum of 18°C (64°F) and a maximum of 31°C (89°F), averaging 24°C (76°F). Notably, April experiences much less rainfall, with just 118 mm (4.6 in) over 24 days and lower humidity at 67%. For more detailed insights, you can check San Ramon weather in April.
In September, the weather tends to be slightly warmer with average temperatures ranging from a minimum of 18°C (66°F) to a maximum of 29°C (85°F), while May offers slightly higher averages, with temperatures ranging from 19°C (67°F) to 30°C (86°F). Both months experience a significant amount of precipitation, with September receiving 461 mm (18.2 in) over 29 days, compared to May's 412 mm (16.2 in) over 30 days. Additionally, September is more humid at 81%, while May's humidity is lower at 69%. For a detailed overview of May weather, you can visit San Ramon weather in May.
In comparing September and June weather, both months feature mild temperatures, but September tends to be slightly cooler, with average temperatures ranging from 18°C (66°F) to a maximum of 29°C (85°F), while June has a slightly warmer range from 19°C (66°F) to a maximum of 30°C (86°F). Additionally, September experiences higher precipitation, totaling 461 mm (18.2 in), compared to June's 397 mm (15.6 in), although both months have similar rain distribution over nearly the entire month—29 and 30 days, respectively. Humidity levels are also quite comparable, with September at 81% and June at 84%. For those looking for detailed weather information specific to June, check out San Ramon weather in June.
In comparing the weather of September and July, we see some noteworthy differences. September sees slightly cooler temperatures with a minimum of 18°C (66°F) and an average of 23°C (74°F), whereas July maintains a minimum of 19°C (67°F) and an average of 24°C (75°F). Both months have a maximum temperature of 29°C (85°F), but September experiences significantly higher precipitation at 461 mm (18.2 in) over 29 days, compared to July's 296 mm (11.7 in) spread across 30 days. Additionally, humidity levels are higher in July at 85%, slightly surpassing September's 81%. For more details on July's climate, you can visit San Ramon weather in July.
September weather is characterized by slightly lower minimum temperatures compared to August, with a minimum of 18°C versus August’s 19°C. Both months share the same average temperature of 23°C, but September sees a maximum temperature of 29°C, one degree cooler than August's peak of 30°C. Precipitation is notably higher in September, with 461 mm compared to August's 393 mm, although both months experience rain on nearly every day. Humidity remains fairly similar, with September at 81% and August at 82%. For a detailed look at the weather patterns of August, you can refer to San Ramon weather in August.
In comparing the weather of September and October, we see notable similarities and differences. Both months feature a minimum temperature of 18°C (66°F) and an average temperature of 23°C (73-74°F), maintaining a warm climate overall. However, October tends to be slightly cooler at the maximum temperature, reaching only 29°C (84°F) compared to September's 29°C (85°F). Rainfall also varies significantly; September experiences 461 mm (18.2 in) of precipitation over 29 days, while October sees an increase to 639 mm (25.2 in) across 30 days. This results in comparable humidity levels, with September at 81% and October slightly lower at 80%. For more detailed information, you can check San Ramon weather in October.
In September, the weather is characterized by slightly higher precipitation levels, with a total of 461 mm spread over 29 days, resulting in a humid atmosphere at 81%. The temperature range remains consistent, with a minimum of 18°C (66°F), an average of 23°C (74°F), and a maximum reaching 29°C (85°F).
In contrast, November sees a reduction in rainfall to 251 mm over 28 days, contributing to a slightly less humid environment at 80%. Despite this decrease in precipitation, the temperature remains unchanged, with the same minimum, average, and maximum readings as in September. For more detailed information, you can check San Ramon weather in November.
September and December showcase contrasting weather patterns, despite having similar average temperatures, with September experiencing slightly higher rainfall and humidity levels. In September, temperatures range from a minimum of 18°C (66°F) to a maximum of 29°C (85°F), accompanied by significant precipitation of 461 mm (18.2 in) over 29 days and an average humidity of 81%. In contrast, December sees a similar temperature range, from 18°C (65°F) to 30°C (86°F), but with much lower precipitation at just 72 mm (2.8 in) over 18 days and a more comfortable humidity of 72%. For detailed insights into December's weather, you can visit San Ramon weather in December.
In September, San Ramon experiences a notable shift in weather characterized by increased humidity and frequent precipitation. Unlike the drier months, this month showcases a lush tropical ambiance, with rain showers dominating nearly every day and contributing to a vibrant landscape. The temperatures remain relatively mild, balancing comfortably around 23°C, while the high humidity often makes the air feel warmer. These elements combine to create a uniquely verdant atmosphere that sets September apart from the typically sunnier and drier months. For a more detailed overview, explore the full insights on San Ramon Climate.