Saint John
United States Virgin Islands, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Saint John, VI

Beautiful scenery with green vegetation, and the vast blue water around the islands in St John, a cloudy and sunny sky with a great beach scene
Beautiful scenery with green vegetation, and the vast blue water around the islands in St John, a cloudy and sunny sky with a great beach scene
September, the first month of the autumn, in Saint John, is still a tropical month, with temperature in the range of an average low of 75.2°F (24°C) and an average high of 87.8°F (31°C).

Temperature

The warmest months are August and September, with an average high-temperature of 87.8°F (31°C).

Rainfall

In Saint John, United States Virgin Islands, it is raining for 16 days, with typically 5.6" (143mm) of accumulated precipitation. Throughout the year, there are 156 rainfall days, and 49.7" (1262mm) of precipitation is accumulated.

Ocean temperature

September and October, with an average ocean temperature of 84.2°F (29°C), are months with the warmest seawater. For any water activity, surface water temperatures between 77°F (25°C) and 84.2°F (29°C) are considered as excellent and extremely pleasant for lengthened periods.

Daylight

In September, the average length of the day is 12.2h.

Sunshine

In September, the average sunshine is 8h.

UV index

March through September, with an average maximum UV index of 12, are months with the highest UV index. A UV Index reading of 11, and higher, represents an extreme threat to health from unprotected exposure to the Sun's UV rays for average individuals.
The daily maximum UV index of 12 interpret into the following advice:
Practice all-important precautions. Light skin people may get burned in less than 5 minutes. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun. Even on cloudy days, a sunscreen with a minimum 30 sun protection factor should be generously applied and frequently re-applied, including after every swim or outdoor exercise. Caution! The reflection of sand and water significantly increases the intensity of the Sun's UV radiation.

What is the warmest month in Saint John?

Warmest months in Saint John are August and September, with an average high-temperature of 87.8°F (31°C).

What is the temperature in September in Saint John?

In September, in Saint John, the average high-temperature is 87.8°F (31°C), and the average low-temperature is 75.2°F (24°C).

How much does it rain in Saint John in September?

In Saint John, in September, during 16 rainfall days, 5.6" (143mm) of precipitation is typically accumulated.

What months are the ocean warmest in Saint John?

September and October, with an average ocean temperature of 84.2°F (29°C), are months with the warmest seawater in Saint John, United States Virgin Islands. For any water activity, surface water temperatures between 77°F (25°C) and 84.2°F (29°C) are considered as excellent and extremely pleasant for lengthened periods.

What is the ocean temperature in September in Saint John?

In Saint John, in September, the average water temperature is 84.2°F (29°C). For swimming, diving, and other water activities, temperatures between 77°F (25°C) and 84.2°F (29°C) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

What is the average length of the day in September in Saint John?

In Saint John, the average length of the day in September is 12.2h.

How long on average sun shines in September in Saint John?

The average sunshine in September in Saint John is 8h.

When is the highest UV index in Saint John?

March through September, with an average maximum UV index of 12, are months with the highest UV index in Saint John, United States Virgin Islands.

What is the UV index intensity in September in Saint John?

In September, the average daily maximum UV index in Saint John is 12. A UV Index estimate of 11, and higher, represents an ultimate hazard to health from unprotected exposure to the UV radiation.
Average temperature in September - Saint John, VI
  • Average high temperature in September: 88°F

Warmest months (with the highest average high temperature) are August and September (88°F).
Months with the lowest average high temperature are January, February, March and December (82°F).

  • Average low temperature in September: 75°F

Months with the highest average low temperature are June, July, August, September and October (75°F).
Coldest months (with the lowest average low temperature) are January, February and March (70°F).

Average rainfall in September - Saint John, VI
  • Average rainfall in September: 5.6"

Wettest months (with the highest rainfall) are October and November (6.3").
The driest month (with the lowest rainfall) is February (2.1").

Average rainfall days in September - Saint John, VI
  • Average rainfall days in September: 16 days

Months with the highest number of rainy days are September and October (16 days).
The month with the lowest number of rainy days is April (9 days).

Average sea temperature in September - Saint John, VI
  • Average sea temperature in September: 84°F

Best months for swimming (with the highest average sea temperature) are September and October (84°F).
Coldest months (with the lowest average sea temperature) are January, February, March and April (79°F).

Average daylight in September / Average sunshine in September - Saint John, VI
  • Average daylight in September: 12.2h

The month with the longest days is June (Average daylight: 13.2h).
The month with shortest days is December (Average daylight: 11h).

  • Average sunshine in September: 8h

Months with most sunshine are March, April, July and August (Average sunshine: 9h).
Months with least sunshine are November and December (Average sunshine: 7).

Average UV index in September - Saint John, VI
  • Average UV index in September: 12

Months with the highest UV index are March, April, May, June, July, August and September (UV index 12).
The month with the lowest UV index is December (UV index 7).