Monthly weather forecast and climate
Port Jefferson, NY

Weather in January

January, the same as December, is another cold winter month in Port Jefferson, New York, with average temperature fluctuating between 37.6°F (3.1°C) and 29.1°F (-1.6°C). January is the coldest month, with an average high-temperature of 37.6°F (3.1°C) and an average low-temperature of 29.1°F (-1.6°C). Weather in January »

Weather in February

February, the last month of the winter, in Port Jefferson, is also a wintry month, with temperature in the range of an average low of 30.4°F (-0.9°C) and an average high of 38.8°F (3.8°C). In Port Jefferson, the average high-temperature is almost the same as in January - a still wintry 38.8°F (3.8°C). Weather in February »

Weather in March

March, the first month of the spring, in Port Jefferson, is a chilly month, with temperature in the range of an average high of 43.9°F (6.6°C) and an average low of 36°F (2.2°C). In March, the average high-temperature is relatively the same as in February - a chilly 43.9°F (6.6°C). Weather in March »

Weather in April

April in Port Jefferson, New York, is a fresh spring month, with average temperature varying between 44.6°F (7°C) and 52.9°F (11.6°C). In Port Jefferson, the average high-temperature rises, from a frosty 43.9°F (6.6°C) in March, to a cool 52.9°F (11.6°C). Weather in April »

Weather in May

The last month of the spring, May, is a comfortable month in Port Jefferson, New York, with average temperature fluctuating between 53.6°F (12°C) and 62.6°F (17°C). In Port Jefferson, the average high-temperature in May rises, from a cool 52.9°F (11.6°C) in April, to a comfortable 62.6°F (17°C). Weather in May »

Weather in June

June, the first month of the summer, in Port Jefferson, is an agreeable month, with average temperature varying between 71.2°F (21.8°C) and 63.1°F (17.3°C). In Port Jefferson, the average high-temperature slightly increases, from an enjoyable 62.6°F (17°C) in May, to a pleasant 71.2°F (21.8°C). Weather in June »

Weather in July

July is a warm summer month in Port Jefferson, New York, with average temperature ranging between max 79.2°F (26.2°C) and min 71.1°F (21.7°C). July is the warmest month, with an average high-temperature of 79.2°F (26.2°C) and an average low-temperature of 71.1°F (21.7°C). Weather in July »

Weather in August

August, the last month of the summer, in Port Jefferson, is also a moderately hot month, with average temperature varying between 71.1°F (21.7°C) and 78.4°F (25.8°C). In Port Jefferson, New York, the average high-temperature is essentially the same as in July - a still moderately hot 78.4°F (25.8°C). Weather in August »

Weather in September

September, the first month of the autumn, in Port Jefferson, is still a pleasant month, with average temperature varying between 72.3°F (22.4°C) and 64.8°F (18.2°C). In September, the average high-temperature slightly decreases, from a moderately hot 78.4°F (25.8°C) in August, to a pleasant 72.3°F (22.4°C). Weather in September »

Weather in October

October, the same as September, is another enjoyable autumn month in Port Jefferson, New York, with average temperature fluctuating between 62.6°F (17°C) and 55.4°F (13°C). In Port Jefferson, the average high-temperature drops, from an agreeable 72.3°F (22.4°C) in September, to a comfortable 62.6°F (17°C). Weather in October »

Weather in November

The last month of the autumn, November, is another cool month in Port Jefferson, New York, with average temperature varying between 44.1°F (6.7°C) and 51.8°F (11°C). In November, the average high-temperature drops, from a comfortable 62.6°F (17°C) in October, to a cool 51.8°F (11°C). Weather in November »

Weather in December

December, the first month of the winter, in Port Jefferson, is also a frosty month, with average temperature fluctuating between 36.5°F (2.5°C) and 43.7°F (6.5°C). In Port Jefferson, the average high-temperature marginally drops, from a cool 51.8°F (11°C) in November, to a frosty 43.7°F (6.5°C). Weather in December »
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FAQ

What is the coldest month in Port Jefferson?

With an average high-temperature of 37.6°F (3.1°C) and an average low-temperature of 29.1°F (-1.6°C), January is the coldest month in Port Jefferson, New York.

How many days does it rain in Port Jefferson?

Throughout the year, in Port Jefferson, New York, there are 146.8 rainfall days, and 33.78" (858mm) of precipitation is accumulated.

What is the driest month in Port Jefferson?

January is the month with the least rainfall in Port Jefferson, New York. Rain falls for 6.8 days and accumulates 2.05" (52mm) of precipitation.

When does it snow in Port Jefferson?

January through March, October through December are months with snowfall.

How many days does it snow in Port Jefferson?

Throughout the year, there are 12.6 snowfall days, and 5.59" (142mm) of snow is accumulated.

When is the lowest UV index in Port Jefferson?

Months with the lowest UV index in Port Jefferson are January through March, November and December, with an average maximum UV index of 2.

What month is the ocean coldest in Port Jefferson?

With an average ocean temperature of 39.7°F (4.3°C), February is the month with the coldest seawater.

What is the month with the least sunshine in Port Jefferson?

With an average of 4.7h of sunshine, February has the least sunshine of the year in Port Jefferson.

When does it snow the most in Port Jefferson?

March is the month with the most snowfall in Port Jefferson. Snow falls for 2.3 days and accumulates 2.13" (54mm) of snow.

When it does not snow in Port Jefferson?

April through September are months without snowfall in Port Jefferson, New York.

What is the most humid month in Port Jefferson?

Months with the highest humidity are May and June, with an average relative humidity of 77%.

When are the longest days in Port Jefferson?

The month with the longest days in Port Jefferson is June, with an average of 15.1h of daylight.

What are the months with the highest UV index in Port Jefferson?

June through August, with an average maximum UV index of 6, are months with the highest UV index.

What is the warmest month in Port Jefferson?

The warmest month in Port Jefferson is July, with an average high-temperature of 79.2°F (26.2°C) and an average low-temperature of 71.1°F (21.7°C).

What month has the most sunshine in Port Jefferson?

July has the most sunshine of the year in Port Jefferson, New York, with an average of 10.6h of sunshine.

What is the month with the warmest ocean in Port Jefferson?

With an average ocean temperature of 73.9°F (23.3°C), August is the month with the warmest seawater in Port Jefferson, New York.

What is the least humid month in Port Jefferson?

With an average relative humidity of 71%, November is the least humid month.

What is the wettest month in Port Jefferson?

The month with the most rainfall in Port Jefferson, New York, is December when the rain falls for 11.4 days and typically aggregates up to 3.58" (91mm) of precipitation.

What is the month with the shortest days in Port Jefferson?

The month with the shortest days in Port Jefferson, New York, is December, with an average of 9.3h of daylight.

Average temperature
Port Jefferson, NY

Average temperature - Port Jefferson, NY

The warmest month (with the highest average high temperature) is July (79.2°F).
The month with the lowest average high temperature is January (37.6°F).

Months with the highest average low temperature are July and August (71.1°F).
The coldest month (with the lowest average low temperature) is January (29.1°F).

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Average pressure
Port Jefferson, NY

Average pressure - Port Jefferson, NY

The month with the highest atmospheric pressure is November (30.09").
The month with the lowest atmospheric pressure is June (29.93").

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Average wind speed
Port Jefferson, NY

Average wind speed - Port Jefferson, NY

The windiest month (with the highest average wind speed) is January (12.9mph).
The calmest month (with the lowest average wind speed) is July (8.3mph).

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Average humidity
Port Jefferson, NY

Average humidity - Port Jefferson, NY

Months with the highest relative humidity are May and June (77%).
The month with the lowest relative humidity is November (71%).

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Average rainfall
Port Jefferson, NY

Average rainfall - Port Jefferson, NY

The wettest month (with the highest rainfall) is December (3.58").
The driest month (with the least rainfall) is January (2.05").

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Average rainfall days
Port Jefferson, NY

Average rainfall days - Port Jefferson, NY

The month with the highest number of rainy days is July (16.5 days).
The month with the least rainy days is January (6.8 days).

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Average snowfall
Port Jefferson, NY

Average snowfall - Port Jefferson, NY

The month with the highest snowfall is March (2.13").
Months with the least snowfall are April, May, June, July, August and September (0").

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Average snowfall days
Port Jefferson, NY

Average snowfall days - Port Jefferson, NY

The month with the highest number of snowfall days is February (4.4 days).
Months with the least snowfall days are May, June, July, August and September (0 days).

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Average sea temperature
Port Jefferson, NY

Average sea temperature - Port Jefferson, NY

The best month for swimming (with the highest average sea temperature) is August (74°F).
The coldest month (with the lowest average sea temperature) is February (39.7°F).

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Average daylight / Average sunshine
Port Jefferson, NY

Average daylight / Average sunshine - Port Jefferson, NY

The month with the longest days is June (Average daylight: 15.1h).
The month with the shortest days is December (Average daylight: 9.3h).

The month with the most sunshine is July (Average sunshine: 10.6h).
The month with the least sunshine is February (Average sunshine: 4.7h).

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Average sunshine days
Port Jefferson, NY

Average sunshine days - Port Jefferson, NY

The month with the most sunshine days is November (20.5 days).
The month with the least sunshine days is July (13 days).

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Average UV index
Port Jefferson, NY

Average UV index - Port Jefferson, NY

Months with the highest UV index are June, July and August (UV index 6).
Months with the lowest UV index are January, February, March, November and December (UV index 2).

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Average visibility
Port Jefferson, NY

Average visibility - Port Jefferson, NY

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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