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September Weather in Costa Rica, Peru

Last updated: August 27, 2025

In September, the average temperature in Costa Rica, Peru reaches a pleasant 26°C (79°F). Expect a cozy minimum of 18°C (64°F) and a warm maximum of 36°C (97°F). The region experiences an average precipitation of 53 mm (2.1 in) over 10 days, accompanied by a moderate humidity level of 42%.

September Temperature in Costa Rica

In September in Costa Rica, the average temperature is 26°C (79°F). Maximums can reach 36°C (97°F), and minimums can be as low as 18°C (64°F). This pleasant climate makes it an ideal time for outdoor activities and exploring the local attractions.

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 26°C (79°F), with highs reaching up to 36°C (97°F) and lows dropping to around 18°C (64°F).
JanFebMarAprMayJunJulAugSepOctNovDec777777777675757778797877
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 53 mm (2.1 in) spread over a duration of 10 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 53 mm (2.1 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec21721224217414894626153146247220
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 26°C (79°F), this humidity feels like a comfortable embrace, making it ideal for exploring the sights and sounds of the area without feeling too sticky or uncomfortable.

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.
JanFebMarAprMayJunJulAugSepOctNovDec80%76%81%86%86%70%47%37%42%62%76%89%
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.
JanFebMarAprMayJunJulAugSepOctNovDec151616161411111214151414
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 Weather25°C (77°F)217 mm (8.5 inches)80%extreme
February Weather25°C (77°F)212 mm (8.4 inches)76%extreme
March Weather25°C (77°F)242 mm (9.5 inches)81%extreme
April Weather25°C (77°F)174 mm (6.9 inches)86%extreme
May Weather25°C (76°F)148 mm (5.8 inches)86%extreme
June Weather24°C (76°F)94 mm (3.7 inches)70%extreme
July Weather24°C (75°F)62 mm (2.5 inches)47%extreme
August Weather25°C (77°F)61 mm (2.4 inches)37%extreme
September Weather26°C (79°F)53 mm (2.1 inches)42%extreme
October Weather26°C (79°F)146 mm (5.7 inches)62%extreme
November Weather25°C (78°F)247 mm (9.7 inches)76%extreme
December Weather25°C (78°F)220 mm (8.7 inches)89%extreme

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