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September Weather in Costa Rica, Brazil

Last updated: August 22, 2025

In Costa Rica, Brazil, the average temperature in September hovers around 24°C (75°F). Expect a range where the temperature can dip to a cool 8°C (46°F) or spike to a sweltering 39°C (102°F). During this month, anticipate 57 mm (2.2 in) of precipitation over approximately 6 days, paired with an average humidity of 42%.

September Temperature in Costa Rica

In September, in Costa Rica, the average temperature is 24°C (75°F). Maximums can reach 39°C (102°F) and minimums can be as low as 8°C (46°F). This makes it a great time to enjoy various outdoor activities while being prepared for both warm and cooler evenings.

September Weather in Costa Rica: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Costa Rica, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Costa Rica, September typically has an average temperature of 24°C (75°F), with highs reaching up to 39°C (102°F) and lows dropping to around 8°C (46°F).
JanFebMarAprMayJunJulAugSepOctNovDec797877736865646775767778
Data source: Temperature data for Costa Rica generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Costa Rica

In Costa Rica in September, the precipitation amount is 57 mm (2.2 in) over a span of 6 days.

September Precipitation Trends in Costa Rica

The chart displays monthly precipitation patterns in Costa Rica, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Costa Rica, September typically receives around 57 mm (2.2 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec160131146639888239557176100216
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Costa Rica

In Costa Rica in September humidity is 42%. With an average temperature of 24°C (75°F), this humidity feels like a comfortable and pleasant environment for traveling, allowing you to explore the sights without feeling overly sticky or fatigued.

September Average Humidity in Costa Rica

This chart illustrates the average monthly humidity levels in Costa Rica, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Costa Rica is approximately 42%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%83%82%76%67%61%52%42%42%43%68%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Costa Rica

In Costa Rica in September, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in Costa Rica.

Maximum UV Index Levels in Costa Rica for September

The chart shows the monthly maximum UV Index (UVI) for Costa Rica in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Costa Rica typically reaches 11, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec15151311867911141515
Data source: Costa Rica September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Costa Rica Compares to Other Months

Weather in Costa Rica varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Costa Rica, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Costa Rica, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather26°C (79°F)160 mm (6.3 inches)85%extreme
February Weather25°C (78°F)131 mm (5.1 inches)83%extreme
March Weather25°C (77°F)146 mm (5.8 inches)82%extreme
April Weather23°C (73°F)63 mm (2.5 inches)76%extreme
May Weather20°C (68°F)98 mm (3.9 inches)67%very high
June Weather18°C (65°F)88 mm (3.5 inches)61%high
July Weather18°C (64°F)23 mm (0.9 inches)52%high
August Weather20°C (68°F)94 mm (3.7 inches)42%very high
September Weather24°C (75°F)57 mm (2.2 inches)42%extreme
October Weather24°C (76°F)176 mm (6.9 inches)43%extreme
November Weather25°C (77°F)100 mm (3.9 inches)68%extreme
December Weather26°C (78°F)216 mm (8.5 inches)84%extreme

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