September weather forecast
Costa Rica

September in Costa Rica is known as one of the wettest months of the year, marking the height of the "Green Season." Rain showers are frequent and often heavy, but they significantly contribute to the country's lush, green landscapes. Average temperatures during September range from 20°C (68°F) to 25°C (77°F), somewhat cooler than the preceding months due to the abundant rainfall.

In the central highlands, which encompass regions like San Jose and the Cordillera Central, temperatures typically vary from 18°C (64.4°F) to 20°C (68°F). Despite the high likelihood of rain, the region's breathtaking scenery and rich biodiversity can still be appreciated during breaks in the precipitation.

On the Caribbean coast, the pattern of constant rainfall remains the norm in September. However, the region's unique biodiversity and multiple nature reserves continue to attract visitors despite the increased rain.

While September does not see the temperature extremes of the hotter months, it is noted for its high rainfall. Visitors during this period should be prepared for humid days interspersed with frequent, often heavy, showers.

As September gives way to October, the high precipitation levels persist, and the country braces itself for the rainiest month of the year. Despite the wet conditions, visitors in September can enjoy the vibrant, rain-soaked landscapes at their most lush and verdant, alive with a wide array of wildlife.

---

• San José - September »
  The months with the highest humidity in San José are September and October, with an average relative humidity of 91%. On the first day of September in San José, sunrise is at 05:27 and sunset at 17:45.
• Limon - September »
  September is the warmest month in Limon, with the temperature often reaching an average high of 30.6°C (87.1°F) and an average low of 22.4°C (72.3°F). With an average high-temperature of 30.6°C (87.1°F) and an average low-temperature of 22.4°C (72.3°F), September is the warmest month in Limon.
• Alajuela - September »
  In Alajuela in September, it is raining for 29.3 days, with typically 321mm (12.64") of accumulated precipitation. September, in Alajuela, Costa Rica, experiences daily high and low temperatures similar to the earlier months, while embracing other changes in weather parameters.
• Puntarenas - September »
  The month with the most rainfall in Puntarenas, Costa Rica, is September, when the rain falls for 24.3 days and typically aggregates up to 296mm (11.65") of precipitation. In Puntarenas in September, during 24.3 rainfall days, 296mm (11.65") of precipitation is typically accumulated.
• Liberia - September »
  In Liberia during September, the rain falls for 27.7 days and regularly aggregates up to 187mm (7.36") of precipitation. On the first day of September in Liberia sunrise is at 05:32 and sunset at 17:50.
• Guadalupe - September »
  September and October, with an average relative humidity of 86%, are the most humid months in Guadalupe. In Guadalupe, in September, during 29.6 rainfall days, 267mm (10.51") of precipitation is typically accumulated.
• San Francisco - September »
  January through April, June, July, September, October and December, with an average maximum UV index of 6, are months with the highest UV index in San Francisco. Transitioning from August to September, San Francisco observes an average high-temperature of a still warm 26.3°C (79.3°F), differing subtly from the previous month.
• San Isidro - September »
  In San Isidro, during September, the rain falls for 29.5 days and regularly aggregates up to 344mm (13.54") of precipitation. September marks a shift in the climatological patterns of San Isidro, manifesting a slight dip in the temperature spectrum to 16.4°C (61.5°F) - 23°C (73.4°F).
• Quesada - September »
  The months with the highest humidity in Quesada are September and October, with an average relative humidity of 91%. September weather in Quesada maintains the wet season's magnitude, making it one of the wettest months, with rainfall reaching 344mm (13.54").
• San Vicente - September »
  January through April, June, July, September, October and December, with an average maximum UV index of 6, are months with the highest UV index in San Vicente, Costa Rica. In San Vicente during September, the rain falls for 29.4 days and regularly aggregates up to 288mm (11.34") of precipitation.
• San Rafael - September »
  The temperature in San Rafael lowers to an average of 16.5°C (61.7°F) during September nights. In San Rafael, in September, during 29.7 rainfall days, 320mm (12.6") of precipitation is typically accumulated.
• San Diego - September »
  In San Diego in September, it is raining for 29.7 days, with typically 320mm (12.6") of accumulated precipitation. September sees an escalation in rainfall back to 320mm (12.6"), as the month stands shoulder to shoulder with the showers that define San Diego's weather.