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Costa RicaThe weather in September in Guanacaste
It's warm in September in Guanacaste with an average temperature of 28°C. Temperatures this month range from a low of 27°C to a high of 29°C. At night, you can expect temperatures between 20°C and 21°C.
Looking for sun? September isn’t a good month to be in Guanacaste. The temperature is nice, but there’s too much chance of rain.
Average temperatures and precipitation
This chart shows the average daily maximum and minimum temperatures (in degrees Celsius) and precipitation (in millimeters) in September for Guanacaste, Costa Rica. A low precipitation value usually indicates little to no rainfall on that day in recent years, while a higher value suggests more frequent rainfall.
Temperature records
With 34°C in 2021, Guanacaste reached the highest temperature in September over the past 10 years. The lowest daytime temperature in this month was 23°C in 2014. The extreme nighttime temperatures ranged from a lowest recorded value of 16°C to a highest value of 24°C.
Rainfall amount
In September, there is an average of 362 mm of precipitation, spread over 27 days. The wind speed is around 4 Bft, mostly coming from the South.
Daily weather in September for Guanacaste
Click on any day in September to get detailed info about the usual weather on that day in Guanacaste. Check out the historical temperatures and precipitation over the past 10 years on this day.
September weather comparison
| Guanacaste | New York | |
|---|---|---|
| Average temperature | 28°C | 27°C |
| Max. temperature | 29°C | 31°C |
| Min. temperature | 20°C | -5°C |
| Total precipitation | 362 mm | 57 mm |
| Rainy days | 27 days | 9 days |
Start of September
The month of September starts in Guanacaste with hot temps, averaging around 28°C during the day and nights around 21°C.
Mid September
By mid-September, daytime temps rise to around 29°C, with nights around 21°C. There’s a high chance of precipitation during this time.
End of September
By the end of September, the average daytime temperature in Guanacaste is around 29°C, while nighttime temps are about 21°C. There’s a significant chance of many days with precipitation.
Find affordable vacations to Guanacaste
UV index
The UV index is a maximum of 9 this month. That's a very high value on the intensity scale of 1 to 11. Unprotected skin can burn within 10-15 minutes.
The hurricane season in Guanacaste runs from June to November.
Check out the climate of Guanacaste for all months and discover the best travel time
Temperature charts
These charts show the average temperatures in September in Guanacaste, Costa Rica. The temperatures are shown in degrees Celsius and are calculated based on data from the past 10 years.
Daily Temperature in September in Guanacaste
Temperature in September in Guanacaste over the years
Precipitation charts
These charts show the average amount of precipitation in September in Guanacaste, Costa Rica. Precipitation is always measured as water, even when it falls as snow or hail The amount of precipitation is displayed in millimeters, while snowfall is shown in centimeters.
Daily Precipitation in September in Guanacaste
Total precipitation in September in Guanacaste over the years
Daily UV index in September in Guanacaste
This chart shows the average daily UV index in September in Guanacaste, with the UV index ranging from 0 to a maximum of 11. The bottom of the chart shows the days of the month. Based on historical data, this chart provides an idea of the daily UV radiation levels you can expect.
Weather experiences in September in Guanacaste
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Average weather in Guanacaste by month
Click on a month below to see detailed weather info for Guanacaste. Based on historical weather data, you can see the average temperature, precipitation, wind, and UV index for each day of the month.