Last updated: August 21, 2025
September in San Jose, Costa Rica, is characterized by a cool and humid climate, where maximum temperatures reach 25°C (78°F). The average temperature hovers around 19°C (66°F), while nights can dip to a refreshing 14°C (58°F). This month is marked by significant rainfall, with precipitation totaling 379 mm (14.9 in), occurring on 29 days of the month, resulting in lush, vibrant scenery. The humidity level remains high at 81%, contributing to the tropical atmosphere that defines this central valley city during the rainy season.
In September, San Jose, Costa Rica experiences mild and pleasant temperatures, with minimums around 14°C (58°F) and average highs of 25°C (78°F). This month sees a slight dip in temperatures from the preceding month, maintaining a comfortable average of 19°C (66°F). As the rainy season peaks, the refreshing coolness can make the city feel invigorating, perfect for exploring its vibrant culture and lush surroundings. The steady highs and lows indicate a consistent climate, making September an ideal time for eco-tourism and experiencing the lush beauty of Costa Rica's landscapes.
In September, San Jose, Costa Rica, experiences a significant surge in rainfall, with precipitation reaching 379 mm (14.9 in) over 29 days. This marks a continuation of the region's wet season, following the already substantial rains of August. The trend reveals a steady increase in precipitation as the year progresses, peaking in October with 517 mm (20.4 in). The consistency of rainfall days in September mirrors the month's high totals, showcasing a lush, verdant landscape that thrives in this tropical climate. As the rainy season rolls forward, residents and visitors alike can expect the vibrant greenery that defines Costa Rica's natural beauty.
In September, San Jose, Costa Rica experiences a notable dip in humidity, recorded at 81%. This slight decrease follows the peak levels reached during the preceding months of June and July, which boast humidity percentages of 84% and 85%, respectively. As the rainy season progresses, the humidity remains relatively high, yet shows a moderate decline from the summer's intensity. By October, conditions shift further as humidity figures ease to 80%, signaling the gradual transition towards the drier months. Overall, September serves as a bridge, maintaining the tropical climate's characteristic moisture while hinting at the season's impending change.
September in San Jose, Costa Rica, continues the trend of extreme UV exposure, with a consistent UV Index of 14. This month joins the ranks of the summer months, where outdoor enthusiasts should remain cautious, as the burn time is just 10 minutes. With its unwavering intensity, September's index echoes the patterns seen from January through August, where the UV levels have firmly remained high. As you soak in the vibrant local culture and stunning landscapes, don’t forget to protect your skin to avoid burns. Stay informed and plan your outdoor activities wisely by checking the San Jose UV Index for the latest updates!
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September in San Jose, Costa Rica, offers a delightful blend of sunshine, with 249 hours of sunlight, marking a slight uptick from the preceding months of July and August. While the sun's rays may not reach the heights of March's impressive 329 hours, September still presents more brightness than the cooler, cloudier days of the mid-year, showcasing a vibrant transition toward the rainy season. This month serves as a reminder of the steady warmth that characterizes Costa Rica's climate, allowing residents and visitors alike to bask in pleasant sunshine before the year starts its gradual descent into the cooler months of October and November. With September’s sunlight reflecting an overall trend of fluctuating yet generous illumination throughout the year, it boldly asserts its charm amidst the tropical backdrop.
In San Jose, Costa Rica, September marks a profound shift in the weather pattern, as the likelihood of sunny days dwindles to a mere 9%. This drop signifies the culmination of the rainy season, where the sun rarely makes an appearance, especially in comparison to the earlier months of the year—where January boasts a sunny forecast of 47%. Notably, the trend indicates that as summer fades, the chances for clear skies diminish significantly, with August plummeting to just 6% sun exposure. While the foliage flourishes in the abundant rainfall, if you're dreaming of sunlit adventures in September, you might want to reconsider your plans.
In September, San Jose, Costa Rica, enjoys a consistent 12 hours of daylight, continuing the trend established since March. This month marks a transition within the year, as daylight hours begin to stabilize before gradually decreasing in October. From January to February, the duration of daylight remains at 11 hours, reflecting the city's near-equatorial position. As we move into the lush, vibrant months of March through September, the daylight stretches to a comfortable 12 hours, allowing residents and visitors alike to immerse themselves in the natural beauty and outdoor activities that flourish in this vibrant locale. As the year winds down in October, daylight dips once again, returning to the 11-hour mark seen in the early months.
In San Jose, Costa Rica, the winds of September carry a gentle breeze at an average speed of 1.3 m/s (3 mph), marking a slight uptick from the languid currents of August. This month, with its subtle wind, reflects a broader trend of decreasing breeziness that characterizes the mid-year months, where winds dip to their lowest speeds in June and August. However, as the year shifts towards October, this gentle flow becomes a prelude to the invigorating winds of November and December, hinting at a gradual return to stronger gusts that delight locals and visitors alike. Thus, September's winds serve not only as a comforting backdrop but also as an indicator of the climatic transitions in this vibrant city.
Weather in San Jose varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in San Jose, focusing on differences in temperature, rainfall, humidity, and UV levels.
In San Jose, September tends to be much wetter and more humid than January, with average temperatures ranging from a minimum of 14°C (58°F) to a maximum of 25°C (78°F) and significant rainfall of 379 mm (14.9 in) over an average of 29 days. In contrast, January features milder weather with daily temperatures generally between 11°C (53°F) and 24°C (76°F) and much lower precipitation at 93 mm (3.7 in) over just 11 days. The humidity also drops noticeably in January to 68%, creating a more comfortable atmosphere compared to September's 81%. For more detailed information, you can check San Jose weather in January.
September and February present distinct climates. In September, temperatures range from a minimum of 14°C (58°F) to a maximum of 25°C (78°F), with an average of 19°C (66°F). This month is characterized by high humidity at 81%, along with significant precipitation totaling 379 mm (14.9 in) over 29 days. In contrast, February offers slightly cooler temperatures, with a minimum of 11°C (52°F) and an average of 17°C (64°F), still peaking at 25°C (78°F), but with much less precipitation at 43 mm (1.7 in) and only 12 rainy days. The humidity in February is lower, averaging 68%. For more detailed information, you can visit San Jose weather in February.
When comparing the weather in September and March, notable differences emerge. September experiences a slightly higher average temperature, peaking at 25°C (78°F), while March's temperatures hover around 18°C (64°F) on average. Humidity is significantly higher in September at 81%, compared to 66% in March, contributing to a more humid and potentially uncomfortable atmosphere. Additionally, September is characterized by heavy precipitation, with 379 mm (14.9 in) falling over 29 days, making it the wetter month, whereas March sees much lighter rainfall, totaling only 49 mm (1.9 in) across 14 days. For more details on the weather patterns in March, you can refer to San Jose weather in March.
When comparing the weather in September and April, both months share a similar average temperature of 19°C (66°F), but their extremes tell a different story. September experiences a slightly broader temperature range with a minimum of 14°C (58°F) and a maximum of 25°C (78°F), while April has a minimum of 13°C (56°F) and a maximum of 26°C (80°F). However, September is much wetter, seeing a significant 379 mm (14.9 in) of precipitation over 29 days, compared to April's much milder 113 mm (4.4 in) across 23 days. The humidity is also higher in September at 81%, whereas April's humidity is a more comfortable 67%. For more detailed information on April weather, you can visit San Jose weather in April.
September and May in San Jose exhibit some similarities, but also key differences in weather conditions. Both months experience a minimum temperature of 14°C (58°F) and an average temperature around 19°C (66-67°F), with maximum temperatures slightly higher in May at 26°C (79°F) compared to September's 25°C (78°F). However, September tends to be wetter, with a precipitation total of 379 mm (14.9 in) compared to May's 425 mm (16.7 in), despite both months having rain on 29 days. Additionally, September's humidity is higher at 81%, creating a more tropical feel, while May maintains a lower humidity level of 69%. For a more detailed look at May's weather, check out San Jose weather in May.
When comparing the weather in September and June, both months show similar average temperatures, with September recording a minimum of 14°C (58°F) and a maximum of 25°C (78°F), and June slightly warmer with a minimum of 15°C (59°F) and a maximum of 26°C (78°F). However, September is characterized by a higher level of precipitation, totaling 379 mm (14.9 in) over 29 days, compared to June's 341 mm (13.4 in) over 28 days. Additionally, September has a humidity level of 81%, which is slightly lower than June's 84%. For a detailed look at June's weather specifics, you can visit San Jose weather in June.
In comparing the weather of September to that of July, we see some notable differences. September experiences slightly cooler temperatures, with minimums of 14°C (58°F) compared to July's 15°C (59°F), while both months share an average and maximum temperature of 19°C (66°F) and 25°C (78°F), respectively. However, September is significantly wetter, with 379 mm (14.9 in) of precipitation over 29 days, compared to July's 266 mm (10.5 in) over 28 days. Additionally, September has a humidity level of 81%, slightly lower than July's 85%. For a more detailed look at July weather, you can visit San Jose weather in July.
In comparing the weather of September and August, both months exhibit similar average temperatures, with September having a minimum of 14°C (58°F) and a maximum of 25°C (78°F), while August ranges slightly higher with a minimum of 15°C (59°F) and a maximum of 26°C (79°F). Precipitation is notably heavier in September, totaling 379 mm (14.9 in) over 29 days compared to August’s 304 mm (12.0 in) across 28 days. Additionally, humidity levels remain relatively high throughout both months, with September at 81% and August at 82%, indicating a consistently moist environment. For a closer look at August's weather specifics, you can refer to San Jose weather in August.
In comparing the weather between September and October, both months show similar temperature patterns, with minimums of 14°C (58°F), averages of 19°C (66°F), and maximums of 25°C (78°F). However, October experiences a notable increase in precipitation, with 517 mm (20.4 in) compared to September's 379 mm (14.9 in), maintaining the same frequency of rain over 29 days. Humidity levels remain similar, with October slightly lower at 80% compared to September's 81%. For a more detailed look into October's weather patterns, you can visit San Jose weather in October.
In comparing the weather between September and November, we can see some nuanced differences. September typically features slightly warmer temperatures, with an average of 19°C (66°F) and a maximum of 25°C (78°F), while November has a cooler average of 18°C (65°F) and a maximum of 24°C (75°F). Precipitation levels are notably higher in September, with 379 mm (14.9 in) recorded over 29 days, compared to November's 260 mm (10.3 in) across 24 days. Humidity remains quite similar, with September at 81% and November slightly lower at 80%. Overall, November tends to be a bit drier and cooler than September. For more detailed information, you can check San Jose weather in November.
In comparing the weather of September and December, September typically experiences slightly warmer temperatures, with an average of 19°C (66°F) and highs reaching up to 25°C (78°F). In contrast, December sees a cooler average of 18°C (64°F) and a maximum of 24°C (75°F). Precipitation is significantly higher in September, with 379 mm (14.9 in) over 29 days, while December has a much lower total of 156 mm (6.1 in) over just 16 days. Humidity also drops from 81% in September to 72% in December, making the latter month feel a bit drier. For more details, you can check out San Jose weather in December.
As September unfolds in San Jose, the weather takes on a distinctive character, marked by increased humidity and frequent rain showers that create a lush, vibrant atmosphere. While temperatures remain pleasantly mild, averaging around 19°C, the city experiences a notable shift from the drier months, with nearly the entire month featuring significant precipitation. This transition not only revitalizes the landscape but also brings about a unique charm to the city, enhancing its natural beauty. For those interested in a deeper understanding of how September compares to other months, you can explore more in our detailed overview of San Jose Climate.