September weather forecast
Saint John, VI

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Beautiful scenery with green vegetation and the vast blue water around the islands in St John, Virgin Islands
Beautiful scenery with green vegetation and the vast blue water around the islands in St John, Virgin Islands

Weather in September

Despite heading towards the tail end of summer, September in Saint John brings no reprieve from the warmth. The tropical maritime climate is at its zenith during this period, with plenty of sun-soaked days to enjoy. The high point featuring September weather is the substantial increase in rainfall, registering a notable 5.6" (142mm). Locals and visitors can expect an interplay of hot sunny days and refreshing evening showers.

Temperature

Saint John sees the highest average temperatures during the months of August and September, peaking at 87.8°F (31°C).

Rainfall

In Saint John, during September, the rain falls for 16 days and regularly aggregates up to 5.63" (143mm) of precipitation. Throughout the year, there are 156 rainfall days, and 49.69" (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.
Note: For engaging in any water activities, temperatures from 77°F (25°C) to 84.2°F (29°C) are viewed as outstanding and exceptionally pleasing for prolonged durations.

Daylight

The average length of the day in September is 12h and 14min.
On the first day of the month, sunrise is at 6:04 am and sunset at 6:32 pm. On the last day of September, sunrise is at 6:09 am and sunset at 6:08 pm AST.

Sunshine

In Saint John, the average sunshine in September is 8h.

UV index

The months with the highest UV index are March through September, with an average maximum UV index of 12. A UV Index estimate of 11, and higher, represents an extreme health hazard from exposure to the Sun's UV radiation for average individuals.
Note: The daily maximum UV index of 12 in September interprets into the following advice:
Employ every precaution of importance, unprotected skin and eyes could burn within moments. UV radiation from the Sun is most intense between 10 a.m. and 4 p.m. Try to avoid direct sunlight during this period. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days. Even if the day is cloudy, sunscreen with SPF of at least 30 should be applied generously and reapplied often, particularly after swimming or outdoor exercise. Attention! The reflection of both water and sand can increase the intensity of UV rays.

Frequently asked questions

What are the warmest months?

The warmest period is usually observed in August and September, with the average high-temperature peaking at 87.8°F (31°C).

How hot does it get in September?

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 September?

In September, the rain falls for 16 days. Throughout September, 5.63" (143mm) of precipitation is accumulated.

What months are the ocean warmest?

September and October, with an average ocean temperature of 84.2°F (29°C), are months with the warmest seawater.

How warm is the water in September in Saint John?

In Saint John, the average seawater temperature in September is 84.2°F (29°C). Water temperature between 77°F (25°C) and 84.2°F (29°C) is regarded as very warm and enjoyable by all. With these temperatures, water activities are pleasurable, without feeling uncomfortable for prolonged periods.

How many hours of daylight does Saint John have in September?

The average day length in September is 12h and 14min.

When are sunrise and sunset in September?

In September, on the first day of the month, sunrise is at 6:04 am and sunset at 6:32 pm. On the last day of the month, sunrise is at 6:09 am and sunset at 6:08 pm AST.

How many hours of sunshine does Saint John have in September?

In September, the average sunshine duration is 8h.

What is the month with the highest UV index?

March through September, with an average maximum UV index of 12, are months with the highest UV index.

What is the UV index intensity in September?

In September, the average daily maximum UV index is 12. A UV Index of 11, and more, symbolizes an excessive health risk from unsafe exposure to Sun's UV rays.
Average rainfall days
Average daylight
Average sunshine
Average UV index

Average temperature in September
Saint John, VI

Average temperature in September - Saint John, VI
  • Average high temperature in September: 88°F

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

  • Average low temperature in September: 75°F

The months with the highest average low temperature are June, July, August, September and October (75°F).
The 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 - Saint John, VI
  • Average rainfall in September: 5.6"

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

Average rainfall days in September
Saint John, VI

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

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

Average sea temperature in September
Saint John, VI

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

The best months for swimming (with the highest average sea temperature) are September and October (84°F).
The 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 / Average sunshine in September - Saint John, VI
  • Average daylight in September: 12h and 1min

The month with the longest days is June (Average daylight: 13h and 12min).
The month with the shortest days is December (Average daylight: 11h and 6min).

  • Average sunshine in September: 8h

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

Average UV index in September
Saint John, VI

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

The 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).

Saint John, United States Virgin Islands, USA

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