Contents
- Weather in January
- Frequently asked questions
- Average temperature in January
- Average pressure in January
- Average wind speed in January
- Average humidity in January
- Average rainfall in January
- Average rainfall days in January
- Average snowfall in January
- Average snowfall days in January
- Average sea temperature in January
- Average daylight in January
- Average sunshine in January
- Average sunshine days in January
- Average UV index in January
- Average cloud cover in January
- Average visibility in January
Weather in January
Temperature
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).Humidity
In January, the average relative humidity is 72%.Rainfall
January is the month with the least rainfall. Rain falls for 6.8 days and accumulates 2.05" (52mm) of precipitation.Snowfall
January through March, October through December are months with snowfall. In Port Jefferson, in January, during 3.5 snowfall days, 0.94" (24mm) of snow is typically accumulated. In Port Jefferson, during the entire year, snow falls for 12.6 days and aggregates up to 5.59" (142mm) of snow.Ocean temperature
In Port Jefferson, in January, the average water temperature is 42.3°F (5.7°C).Note: At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.
Daylight
In Port Jefferson, the average length of the day in January is 9h and 38min.On the first day of the month, sunrise is at 7:16 am and sunset at 4:34 pm. On the last day of January, sunrise is at 7:03 am and sunset at 5:07 pm EST.
Sunshine
In January, the average sunshine is 5.1h.UV index
The months with the lowest UV index in Port Jefferson are January through March, November and December, with an average maximum UV index of 2. A UV Index reading of 2, and below, represents a low threat to health from exposure to the Sun's UV radiation for the ordinary person.Note: The daily high UV index of 2 during January translates into the following recommendations:
Protection from prolonged sun exposure is necessary for babies, children, and individuals with sensitive skin. UV radiation from the Sun is most dangerous during midday; take precautions and seek shade. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense. Take heed! Reflection from the snow can almost amplify the Sun's UV radiation by double.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What part of the year is the coldest?
How cold is January in Port Jefferson?
What is the average humidity in January?
What is the driest month?
How many days does it rain in January?
How much does it snow in January?
What is the ocean temperature in January?
What is the average length of the day in January?
What time are sunrise and sunset in January?
How many hours of sunshine does Port Jefferson have in January?
What is the month with the lowest UV index?
What is the UV index reading in January?
Average temperature in January
Port Jefferson, NY
- Average high temperature in January: 37.6°F
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).
- Average low temperature in January: 29.1°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 in January
Port Jefferson, NY
- Average pressure in January: 30.04"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 in January
Port Jefferson, NY
- Average wind speed in January: 12.9mph
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 in January
Port Jefferson, NY
- Average humidity in January: 72%
The months with the highest relative humidity are May and June (77%).
The month with the lowest relative humidity is November (71%).
Average rainfall in January
Port Jefferson, NY
- Average rainfall in January: 2.05"
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 in January
Port Jefferson, NY
- Average rainfall days in January: 6.8 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 in January
Port Jefferson, NY
- Average snowfall in January: 0.94"
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 in January
Port Jefferson, NY
- Average snowfall days in January: 3.5 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 in January
Port Jefferson, NY
- Average sea temperature in January: 42.3°F
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 in January /
Average sunshine in January
Port Jefferson, NY
- Average daylight in January: 9h and 4min
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 1min
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 in January
Port Jefferson, NY
- Average sunshine days in January: 19.8 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 in January
Port Jefferson, NY
- Average UV index in January: 2
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 in January
Port Jefferson, NY
- Average cloud cover in January: 45
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 in January
Port Jefferson, NY
- Average visibility in January: 6mi
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).
Port Jefferson, New York, USA
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