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September Weather in Costa Rica, Mexico

Last updated: August 26, 2025

In Costa Rica, Mexico, the average temperature in September is a pleasant 24°C (75°F). You can expect a minimum of 18°C (64°F) and a maximum soaring to 33°C (92°F). Prepare for relatively high humidity, averaging 82%, as well as some rainfall, with 216 mm (8.5 in) of precipitation spread over 23 days.

September Temperature in Costa Rica

In September in Costa Rica, the average temperature is 24°C (75°F). The maximum can reach 33°C (92°F), while the minimum can be as low as 18°C (64°F). This makes Costa Rica an ideal destination for travelers seeking pleasant and comfortable weather.

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 33°C (92°F) and lows dropping to around 18°C (64°F).
JanFebMarAprMayJunJulAugSepOctNovDec707275787875757675737270
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 216 mm (8.5 in) over a period of 23 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 216 mm (8.5 inches) of precipitation spread over approximately 23 days.
JanFebMarAprMayJunJulAugSepOctNovDec138621118305811372161804214
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 82%. With an average temperature of 24°C (75°F), this humidity feels like a warm embrace, making travel feel sticky and heavy on the skin, often requiring more frequent breaks and hydration.

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 82%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%68%59%57%65%66%75%82%82%83%80%76%
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 is 14, which corresponds to an extreme Exposure Category. The time to burn is just 10 minutes, so it's crucial to take precautions. For the detailed hourly UV index in Costa Rica, you can check here.

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 14, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec11131415141415141413119
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 Weather21°C (70°F)13 mm (0.5 inches)76%extreme
February Weather22°C (72°F)8 mm (0.3 inches)68%extreme
March Weather24°C (75°F)6 mm (0.2 inches)59%extreme
April Weather26°C (78°F)21 mm (0.8 inches)57%extreme
May Weather26°C (79°F)118 mm (4.6 inches)65%extreme
June Weather24°C (75°F)305 mm (12.0 inches)66%extreme
July Weather24°C (76°F)81 mm (3.2 inches)75%extreme
August Weather24°C (76°F)137 mm (5.4 inches)82%extreme
September Weather24°C (75°F)216 mm (8.5 inches)82%extreme
October Weather23°C (74°F)180 mm (7.1 inches)83%extreme
November Weather22°C (72°F)42 mm (1.6 inches)80%extreme
December Weather21°C (71°F)14 mm (0.5 inches)76%very high

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