September Weather in San Juan

Last updated: March 2, 2024

The weather in San Juan, United States, during September is characterized by an average temperature of 29°C (84°F). Highs can soar to 39°C (103°F), while lows may dip to 20°C (68°F). Typically, the humidity level in San Juan throughout September hovers around 73%.

20°C (68°F)

Minimum temperature

29°C (84°F)

Average temperature

39°C (103°F)

Maximum temperature

73%

Humidity

Precipitation and Sunshine hours

In September, San Juan averages 96 mm (3.8 inches) of rainfall, typically over the course of 11 rainy days. The month enjoys an average of 12 hours 15 minutes of daylight, with the sun shining for approximately 9 hours 39 minutes each day. Additionally, there is a 60% probability of sunny days during this period.

96 mm (3.8 inches)

Precipitation

11 rainy days

Rainy days

9 hours 39 minutes

Sunshine hours

60%

Chance of sun

UV Index

In September, the UV Index in San Juan reaches a maximum of 11, indicating a level of Extreme exposure. The most intense UV radiation typically occurs between 13:00 and 15:00, during which unprotected skin may burn in as little as 10 minutes.

Average solar exposure data for the current time of the year. Actual values may vary and depend on many factors, such as cloud cover, vegetation cover, surface type, etc.
	07:00	08:00	09:00	10:00	11:00	12:00	13:00	14:00	15:00	16:00	17:00	18:00	19:00
UVI	0	1	2	4	7	10	11	11	9	6	4	2	1
Exposure	Low			Moderate	High	VeryHigh	Extreme		VeryHigh	High	Moderate	Low
Time to burn	45 min			30 min	25 min	15 min	10 min		15 min	25 min	30 min	45 min