September weather forecast
San José, Costa Rica

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Skyscape of San José, Costa Rica in the evening sun
Skyscape of San José, Costa Rica in the evening sun

Weather in September

September ushers in a steady phase in San José's weather. Though there are detectable changes from the preceding month, the temperature settles at a reliable 23°C (73.4°F). The rainfall does not show any drastic shifts, creating a stable framework for the weather to unfold. The city continues to glow under its routine torrent, the wet season lending its distinct hue to the city.

Temperature

San José marks the onset of September with an average high-temperature of a still moderately hot 23°C (73.4°F), a subtle shift from August's 23.3°C (73.9°F). Throughout September, an average low-temperature of 16.4°C (61.5°F) is experienced in San José.

Humidity

The months with the highest humidity in San José are September and October, with an average relative humidity of 91%.

Rainfall

In San José, in September, during 29.5 rainfall days, 344mm (13.54") of precipitation is typically accumulated. In San José, Costa Rica, during the entire year, the rain falls for 287.8 days and collects up to 2585mm (101.77") of precipitation.

Daylight

In San José, the average length of the day in September is 12h and 11min.
On the first day of September in San José, sunrise is at 05:27 and sunset at 17:45. On the last day of the month, sunrise is at 05:24 and sunset at 17:27 CST.

Sunshine

The average sunshine in September in San José, Costa Rica, is 6.5h.

UV index

January through December, with an average maximum UV index of 5, are months with the highest UV index. The months with the lowest UV index are January through December, with an average maximum UV index of 5. A UV Index value of 3 to 5 symbolizes a medium health hazard from unsafe exposure to UV radiation for average individuals.
Note: The maximum daily UV index of 5 during September translates into the following directions:
Guard yourself - An obligation to protect skin and eyes from harm exists. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. In the presence of strong sunlight, it's crucial to wear sunglasses that ward off UVA and UVB rays.
Updated: Jan 26, 2024 | Published by: Weather Atlas | About Us / Weather Forecasting / Data Sources

Frequently asked questions

What is the average September temperature in San José?

The high-temperature, in September, in San José, records 23°C (73.4°F), while the low-temperature is 16.4°C (61.5°F).

What are the most humid months in San José?

The months with the highest humidity are September and October, with an average relative humidity of 91%.

What is the average humidity in September in San José?

In September, the average relative humidity in San José is 91%.

How much does it rain in San José in September?

In San José, during September, the rain falls for 29.5 days and regularly aggregates up to 344mm (13.54") of precipitation.

What is the average length of the day in September in San José?

In San José, Costa Rica, the average day length in September is 12h and 11min.

When are sunrise and sunset in September in San José?

On the first day of September in San José, sunrise is at 05:27 and sunset at 17:45. On the last day of the month, sunrise is at 05:24 and sunset at 17:27 CST.

How long on average sun shines in September in San José?

In San José, Costa Rica, the average sunshine duration in September is 6.5h.

What are the months with the highest UV index in San José?

The months with the highest UV index are January through December, with an average maximum UV index of 5.

What is the month with the lowest UV index in San José?

January through December, with an average maximum UV index of 5, are months with the lowest UV index in San José.

How high is the UV index in September in San José?

In September, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a medium health risk from unprotected exposure to UV radiation.

Average temperature in September
San José, Costa Rica

Average temperature in September - San José, Costa Rica
  • Average high temperature in September: 23°C

The warmest month (with the highest average high temperature) is April (26°C).
The month with the lowest average high temperature is October (22.4°C).

  • Average low temperature in September: 16.4°C

The month with the highest average low temperature is June (17°C).
The coldest month (with the lowest average low temperature) is January (13.8°C).

Average pressure in September
San José, Costa Rica

Average pressure in September - San José, Costa Rica
  • Average pressure in September: 1011.1mbar

The month with the highest atmospheric pressure is January (1012.3mbar).
The month with the lowest atmospheric pressure is October (1010.8mbar).

Average wind speed in September
San José, Costa Rica

Average wind speed in September - San José, Costa Rica
  • Average wind speed in September: 4.3km/h

The windiest month (with the highest average wind speed) is February (10.7km/h).
The calmest month (with the lowest average wind speed) is September (4.3km/h).

Average humidity in September
San José, Costa Rica

Average humidity in September - San José, Costa Rica
  • Average humidity in September: 91%

The months with the highest relative humidity are September and October (91%).
The months with the lowest relative humidity are February and March (75%).

Average rainfall in September
San José, Costa Rica

Average rainfall in September - San José, Costa Rica
  • Average rainfall in September: 344mm

The wettest month (with the highest rainfall) is October (438mm).
The driest month (with the least rainfall) is February (26mm).

Average rainfall days in September
San José, Costa Rica

Average rainfall days in September - San José, Costa Rica
  • Average rainfall days in September: 29.5 days

The month with the highest number of rainy days is October (30.5 days).
The month with the least rainy days is February (12.2 days).

Average daylight in September /
Average sunshine in September
San José, Costa Rica

Average daylight in September / Average sunshine in September - San José, Costa Rica
  • Average daylight in September: 12h and 1min

The month with the longest days is June (Average daylight: 12h and 42min).
The month with the shortest days is December (Average daylight: 11h and 36min).

  • Average sunshine in September: 6h and 3min

The month with the most sunshine is February (Average sunshine: 9h and 12min).
The month with the least sunshine is October (Average sunshine: 5h and 48min).

Average sunshine days in September
San José, Costa Rica

Average sunshine days in September - San José, Costa Rica
  • Average sunshine days in September: 0.1 days

The month with the most sunshine days is March (13.5 days).
The month with the least sunshine days is September (0.1 days).

Average UV index in September
San José, Costa Rica

Average UV index in September - San José, Costa Rica
  • Average UV index in September: 5

The months with the highest UV index are January, February, March, April, May, June, July, August, September, October, November and December (UV index 5).
The months with the lowest UV index are January, February, March, April, May, June, July, August, September, October, November and December (UV index 5).

Average cloud cover in September
San José, Costa Rica

Average cloud cover in September - San José, Costa Rica
  • Average cloud cover in September: 65

The month with the most cloud cover is October (Cloud cover 68).
The month with the least cloud cover is February (Cloud cover 30).

Average visibility in September
San José, Costa Rica

Average visibility in September - San José, Costa Rica
  • Average visibility in September: 6km

The months with the highest visibility are January, February and March (9km).
The months with the lowest visibility are August, September, October and November (6km).

San José, Costa Rica

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