Climate and monthly weather forecastPort Jefferson, NY
Climate and monthly weather forecast
Weather in January
January, like December, in Port Jefferson, New York, is an icy winter month, with temperature in the range of an average high of 37.6°F (3.1°C) and an average low of 29.1°F (-1.6°C). In Port Jefferson, the lowest average temperatures are observed in January, with a high of 37.6°F (3.1°C) and a low of 29.1°F (-1.6°C). Weather in January »Weather in February
The last month of the winter, February, is also an icy month in Port Jefferson, New York, with an average temperature varying between 30.4°F (-0.9°C) and 38.8°F (3.8°C). The start of February sees the average high-temperature at a still cold 38.8°F (3.8°C), showing little difference from January's 37.6°F (3.1°C). Weather in February »Weather in March
The first month of the spring, March, is a frosty month in Port Jefferson, New York, with temperature in the range of an average low of 36°F (2.2°C) and an average high of 43.9°F (6.6°C). The advent of March denotes an average high-temperature of a frosty 43.9°F (6.6°C), subtly different from February's 38.8°F (3.8°C). Weather in March »Weather in April
April in Port Jefferson, New York, is a cool spring month, with temperature in the range of an average low of 44.6°F (7°C) and an average high of 52.9°F (11.6°C). The arrival of April brings a change in Port Jefferson's weather, with average high-temperatures moving from March's chilly 43.9°F (6.6°C) to a fresh 52.9°F (11.6°C). Weather in April »Weather in May
May, the last month of the spring in Port Jefferson, is an enjoyable month, with an average temperature ranging between max 62.6°F (17°C) and min 53.6°F (12°C). The onset of May brings a rise in the average high-temperature, elevating from a cool 52.9°F (11.6°C) in April to an enjoyable 62.6°F (17°C). Weather in May »Weather in June
The first month of the summer, June, is a pleasant month in Port Jefferson, New York, with temperature in the range of an average low of 63.1°F (17.3°C) and an average high of 71.2°F (21.8°C). June introduces a minor temperature shift, with average high-temperatures adjusting from May's refreshing 62.6°F (17°C) 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 temperature in the range of an average low of 71.1°F (21.7°C) and an average high of 79.2°F (26.2°C). Port Jefferson's July weather, marked by an average high temperature of 79.2°F (26.2°C) and an average low temperature of 71.1°F (21.7°C), is the warmest in the year. Weather in July »Weather in August
The last month of the summer, August, is another warm month in Port Jefferson, New York, with an average temperature varying between 78.4°F (25.8°C) and 71.1°F (21.7°C). On the advent of August, Port Jefferson's average high-temperature exhibits a minor adjustment to a still moderately hot 78.4°F (25.8°C) from July's 79.2°F (26.2°C). Weather in August »Weather in September
The first month of the autumn, September, is still a pleasant month in Port Jefferson, New York, with an average temperature varying between 64.8°F (18.2°C) and 72.3°F (22.4°C). September's arrival aligns with a minor decrease in average high-temperatures, from August's warm 78.4°F (25.8°C) to an agreeable 72.3°F (22.4°C). Weather in September »Weather in October
October, like September, in Port Jefferson, New York, is another comfortable autumn month, with an average temperature fluctuating between 62.6°F (17°C) and 55.4°F (13°C). Port Jefferson's weather changes with the onset of October, slightly falling from a pleasant 72.3°F (22.4°C) in September to an enjoyable 62.6°F (17°C). Weather in October »Weather in November
The last month of the autumn, November, is also a fresh month in Port Jefferson, New York, with an average temperature varying between 44.1°F (6.7°C) and 51.8°F (11°C). November's arrival coincides with a drop in the average high-temperature, decreasing from October's refreshing 62.6°F (17°C) to a fresh 51.8°F (11°C). Weather in November »Weather in December
December, the first month of the winter in Port Jefferson, is still a chilly month, with an average temperature ranging between min 36.5°F (2.5°C) and max 43.7°F (6.5°C). Start of December brings a slight shift in the average high-temperature, dipping a bit from November's fresh 51.8°F (11°C) to a frosty 43.7°F (6.5°C). Weather in December »Updated: Aug 29, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
The coldest month is January, 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 month with the least rainfall. Rain falls for 6.8 days and accumulates 2.05" (52mm) of precipitation.
In Port Jefferson, during the entire year, the rain falls for 146.8 days and collects up to 33.78" (858mm) of precipitation.
January through March, October through December are months with snowfall.
Throughout the year, there are 12.6 snowfall days, and 5.59" (142mm) of snow is accumulated.
The months with the lowest UV index are January through March, November and December, with an average maximum UV index of 2.
February is the month with the coldest seawater, with an average ocean temperature of 39.7°F (4.3°C).
The month with the least sunshine is February, with an average of 4.7h of sunshine.
March is the month with the most snowfall. Snow falls for 2.3 days and accumulates 2.13" (54mm) of snow.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from EST to EDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from EDT to EST.
In Port Jefferson, snow does not fall in April through September.
The months with the highest humidity are May and June, with an average relative humidity of 77%.
June has the longest days of the year, with an average of 15h and 6min of daylight.
June through August, with an average maximum UV index of 6, are months with the highest UV index.
The warmest temperatures occur during July, when averages reach a peak of 79.2°F (26.2°C) and a low of 71.1°F (21.7°C).
With an average of 10.6h of sunshine, July has the most sunshine of the year.
With an average ocean temperature of 73.9°F (23.3°C), August is the month with the warmest seawater.
November is the least humid month, with an average relative humidity of 71%.
December is the month with the most rainfall. Rain falls for 11.4 days and accumulates 3.58" (91mm) of precipitation.
The month with the shortest days is December, with an average of 9h and 18min of daylight.
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).
The 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).
Average pressure
Port Jefferson, NY
- Average pressure in January:
30.04"Hg - Average pressure in February:
30.02"Hg - Average pressure in March:
30.05"Hg - Average pressure in April:
29.98"Hg - Average pressure in May:
30.01"Hg - Average pressure in June:
29.93"Hg
- Average pressure in July:
29.95"Hg - Average pressure in August:
29.98"Hg - Average pressure in September:
30.05"Hg - Average pressure in October:
30.01"Hg - Average pressure in November:
30.09"Hg - Average pressure in December:
30.06"Hg
The month with the highest atmospheric pressure is November (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed
Port Jefferson, NY
- Average wind speed in January:
12.9mph - Average wind speed in February:
12.4mph - Average wind speed in March:
12.2mph - Average wind speed in April:
11.2mph - Average wind speed in May:
9.4mph - Average wind speed in June:
8.6mph
- Average wind speed in July:
8.3mph - Average wind speed in August:
8.5mph - Average wind speed in September:
9.8mph - Average wind speed in October:
11.7mph - Average wind speed in November:
12.4mph - Average wind speed in December:
12.7mph
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).
Average humidity
Port Jefferson, NY
The months with the highest relative humidity are May and June (77%).
The month with the lowest relative humidity is November (71%).
Average rainfall
Port Jefferson, NY
- Average rainfall in January:
2.05" - Average rainfall in February:
2.17" - Average rainfall in March:
2.6" - Average rainfall in April:
2.83" - Average rainfall in May:
2.76" - Average rainfall in June:
2.72"
- Average rainfall in July:
3.54" - Average rainfall in August:
3.31" - Average rainfall in September:
2.4" - Average rainfall in October:
3.27" - Average rainfall in November:
2.56" - Average rainfall in December:
3.58"
The wettest month (with the highest rainfall) is December (3.58").
The driest month (with the least rainfall) is January (2.05").
Average rainfall days
Port Jefferson, NY
- Average rainfall days in January:
6.8 days - Average rainfall days in February:
8.8 days - Average rainfall days in March:
10.5 days - Average rainfall days in April:
13.5 days - Average rainfall days in May:
15.3 days - Average rainfall days in June:
14.9 days
- Average rainfall days in July:
16.5 days - Average rainfall days in August:
15.7 days - Average rainfall days in September:
12.6 days - Average rainfall days in October:
13.1 days - Average rainfall days in November:
7.7 days - Average rainfall days in December:
11.4 days
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).
Average snowfall
Port Jefferson, NY
The month with the highest snowfall is March (2.13").
The months with the least snowfall are April, May, June, July, August and September (0").
Average snowfall days
Port Jefferson, NY
- Average snowfall days in January:
3.5 days - Average snowfall days in February:
4.4 days - Average snowfall days in March:
2.3 days - Average snowfall days in April:
0.2 days - Average snowfall days in May:
0 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0.1 days - Average snowfall days in November:
0.6 days - Average snowfall days in December:
1.5 days
The month with the highest number of snowfall days is February (4.4 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
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).
Average daylight / Average sunshine
Port Jefferson, NY
- Average daylight in January:
9h and 36min - Average daylight in February:
10h and 42min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 18min - Average daylight in May:
14h and 30min - Average daylight in June:
15h and 6min
- Average daylight in July:
14h and 48min - Average daylight in August:
13h and 48min - Average daylight in September:
12h and 30min - Average daylight in October:
11h and 6min - Average daylight in November:
9h and 54min - Average daylight in December:
9h and 18min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in January:
5h and 6min - Average sunshine in February:
4h and 42min - Average sunshine in March:
6h and 18min - Average sunshine in April:
8h and 24min - Average sunshine in May:
8h and 42min - Average sunshine in June:
9h and 48min
- Average sunshine in July:
10h and 36min - Average sunshine in August:
10h and 30min - Average sunshine in September:
8h and 54min - Average sunshine in October:
5h and 54min - Average sunshine in November:
5h and 30min - Average sunshine in December:
4h and 48min
The month with the most sunshine is July (Average sunshine: 10h and 36min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).
Average sunshine days
Port Jefferson, NY
- Average sunshine days in January:
19.8 days - Average sunshine days in February:
15.6 days - Average sunshine days in March:
17.3 days - Average sunshine days in April:
15.2 days - Average sunshine days in May:
14.5 days - Average sunshine days in June:
13.1 days
- Average sunshine days in July:
13 days - Average sunshine days in August:
13.3 days - Average sunshine days in September:
15.7 days - Average sunshine days in October:
17 days - Average sunshine days in November:
20.5 days - Average sunshine days in December:
17.6 days
The month with the most sunshine days is November (20.5 days).
The month with the least sunshine days is July (13 days).
Average UV index
Port Jefferson, NY
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).
Average cloud cover
Port Jefferson, NY
The month with the most cloud cover is December (Cloud cover 49).
The month with the least cloud cover is August (Cloud cover 28).
Average visibility
Port Jefferson, NY
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
