December Weather in Port Jefferson, United States

Last updated: February 24, 2025

December in Port Jefferson, United States offers a chilly retreat with temperatures ranging from a maximum of 17°C (62°F) to a brisk minimum of -10°C (15°F). The month presents an average temperature of 5°C (40°F), accompanied by high humidity levels around 80%, creating a crisp atmosphere. Visitors can expect approximately 140 mm (5.5 in) of precipitation over 11 days, making it a month of both rain and potential holiday snow. Whether bundling up for festive events or enjoying the serene winter landscape, December in Port Jefferson charms with its wintry character.

December Temperature in Port Jefferson

In December, Port Jefferson experiences the onset of winter, with temperatures reflecting a distinct chill in the air. The month sees minimums dipping to -10°C (15°F), while the average temperature hovers at 5°C (40°F), providing a stark contrast to the milder conditions of fall. Daytime highs reach up to 17°C (62°F), allowing for some pleasantly cool afternoons but underscoring the transition into colder weather. This month sets the stage for winter's grip, following a clear trend of decreasing temperatures compared to the previous months. Residents and visitors alike can expect crisp air and a cozy atmosphere as the holiday season approaches, making it a picturesque time to enjoy the charm of Port Jefferson.

December Weather in Port Jefferson: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Port Jefferson, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec353640485868757569614840
Data source: Temperature data for Port Jefferson generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Port Jefferson

In Port Jefferson, December marks a significant culmination of the year’s precipitation, with 140 mm (5.5 in) of rain falling over 11 days. This amount is comparable to the more intense rainy months like October but is a slight drop from the heavy downpours often seen in April and July. Notably, December's precipitation reflects the onset of winter weather, showcasing the transition from the more humid summer months. While it doesn't reach the peaks of some earlier months, the consistent rainfall this month plays a crucial role in providing moisture for the landscape as it prepares for the colder winter season, setting the stage for January’s drier conditions.

December Precipitation Trends in Port Jefferson

The chart displays monthly precipitation patterns in Port Jefferson, with values for each month alongside December's data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how December's conditions compare to those of other months.
JanFebMarAprMayJunJulAugSepOctNovDec801121041321198713110394143103140
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Port Jefferson

As December rolls into Port Jefferson, the humidity settles at 80%, reflecting a slight uptick compared to the preceding months. Observing the trends throughout the year, there's a notable pattern of higher humidity levels during the colder months, particularly in January and February, which average around 84% and 82%, respectively. As spring approaches, humidity gradually decreases, reaching its low point in the summer months of June and July, where it dips to around 62% to 69%. However, as autumn fades into winter, the humidity rebounds, evident in November's 82% and December's 80%. This seasonal ebb and flow of moisture in the air not only influences the local climate but also adds a layer of charm to the coastal town during the holiday season.

December Average Humidity in Port Jefferson

This chart illustrates the average monthly humidity levels in Port Jefferson, with December's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how December's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec84%82%81%78%70%69%62%65%68%74%82%80%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Port Jefferson

As the year comes to a close, December in Port Jefferson ushers in a notable decline in UV intensity, with a UV Index of 2, categorized as low. This is a stark contrast to the peak summer months, where the index soared to 10, indicating very high exposure levels and a burn time as short as 15 minutes. In December, residents can comfortably enjoy outdoor activities with a burn time of 45 minutes, providing a safe window for sun exposure. The gradual decrease in the UV Index from summer's highs to winter's lows reflects the seasonal changes and emphasizes the importance of adapting sun safety practices throughout the year. For more detailed information on the UV Index, visit Port Jefferson UV Index.

Maximum UV Index Levels in Port Jefferson for December

The chart shows the monthly maximum UV Index (UVI) for Port Jefferson in December, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec35681010998642
Data source: Port Jefferson December UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

December Sunshine in Port Jefferson

In Port Jefferson, December brings a gentle downturn in sunshine hours, offering 176 hours of daylight, a stark contrast to the brightness of the summer months, such as July with its 343 hours. This seasonal shift marks the transition towards winter, where shorter days invite cozy moments indoors. While December enjoys more sunshine than the earlier winter months of January and November, which receive only 154 and 210 hours respectively, it still falls below the vibrant totals seen in spring and summer. The rising trend from early spring through summer, peaking in June and July, showcases the region's sunny disposition, but as the year closes, December reminds us to embrace the softer light and the beauty of the season's quietude.

Monthly Sunshine Duration in Port Jefferson: December Highlighted

The December sunshine duration represents the total number of hours Port Jefferson experiences direct sunlight during the month of December, excluding cloudy or obstructed periods. This chart compares the sunshine duration of December with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec154h180h258h246h285h319h343h323h282h225h210h176h
Data source: Port Jefferson December Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Port Jefferson During December

In December, Port Jefferson experiences a 32% chance of sunny weather, marking it as one of the cloudier months of the year. This trend reflects a decline in sunny days as the calendar progresses toward winter, especially when compared to the preceding month of November, which boasts a more optimistic 56% chance. The data indicates a noticeable dip in sunshine from fall into winter, with December's likelihood falling well below many earlier months. As the region transitions into the heart of winter, residents and visitors might anticipate more gloomy skies, though there's always a possibility for those rare, brilliant sunny days to brighten the season.

Percentage of Sunny Days in December in Port Jefferson

The chart illustrates the percentage of sunny days in Port Jefferson throughout the year, with December highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Port Jefferson experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec52%31%58%48%43%41%41%32%48%41%56%32%
Data source: Port Jefferson December chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Port Jefferson in December

In Port Jefferson, the ebb and flow of daylight throughout the year paints a vivid picture of seasonal change. December, like January and November, gifts residents with only 9 hours of daylight, marking the year's shortest days. As the year progresses from the winter months into spring, daylight gradually increases, peaking in June at a robust 15 hours. This bright surge then gently recedes, creating a rhythmic cycle where each season brings its own vibe. Notably, March and April stand out as spring awakens the world with longer days, while the comforting embrace of summer in June offers the most sunlight for outdoor adventures. As autumn sets in, daylight begins to wane, inviting the cozy charm of shorter days, reminding us of the ever-changing dance of light and time in this vibrant community.

Average Daylight Hours in Port Jefferson for December

The chart illustrates the variation in daylight duration in Port Jefferson throughout the year, with December highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 35m10h 38m11h 58m13h 19m14h 29m15h 3m14h 44m13h 43m12h 24m11h 3m9h 52m9h 16m
Data source: Port Jefferson daylight hours, calculated by summing the hours between sunrise and sunset for each day.

December Winds in Port Jefferson

As December settles in Port Jefferson, the average wind speed gently hovers around 4.5 m/s (10 mph), reflecting a slight decline from the previous months. This reduction in wind intensity aligns with the trend observed throughout the year, where summer months showcased the calmest breezes, peaking in July and August at just 3.4 m/s (8 mph). Conversely, the late fall months—particularly November—experienced a slight uptick in wind speeds, suggesting a transition towards the more blustery conditions typical of winter. Overall, December brings a milder wind experience compared to the brisker autumn days, making it a cozy time to enjoy the serene winter landscapes of the area.

Average December Wind Speed in Port Jefferson

The chart displays monthly wind speed patterns in Port Jefferson, with values for each month shown alongside December's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how December's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec5.04.94.94.44.33.93.43.44.34.74.64.5 m/s
Data source: Port Jefferson December wind data, generated using information from the Copernicus Climate Change Service.

How December Weather in Port Jefferson Compares to Other Months

The weather in Port Jefferson changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of December's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Port Jefferson and find detailed weather information for every month.

December and January present distinct weather characteristics, with January generally being colder than December. In December, temperatures range from a minimum of -10°C (15°F) to a maximum of 17°C (62°F), averaging around 5°C (40°F). This month experiences higher precipitation, totaling 140 mm (5.5 in) over 11 rainy days, with humidity at 80%. In contrast, January sees a drop in temperatures, with minimums reaching -15°C (6°F) and maximums at 15°C (60°F), averaging 2°C (35°F). Precipitation decreases significantly to 80 mm (3.1 in) over 8 days, while humidity slightly increases to 84%. For a deeper look at January conditions, you can find more information here: Port Jefferson weather in January.

December and February offer distinct but chilly weather patterns. In December, temperatures range from a minimum of -10°C (15°F) to a maximum of 17°C (62°F), with an average temperature of 5°C (40°F). The month experiences substantial precipitation at 140 mm (5.5 in) over approximately 11 days and maintains a humidity level of 80%. In contrast, February is slightly colder, with minimum temperatures dipping to -15°C (6°F) and an average of 2°C (36°F). Although it has a lower overall precipitation of 112 mm (4.4 in) across 12 days, humidity increases slightly to 82%. For more detailed insights, you can visit Port Jefferson weather in February.

When comparing December and March weather, December tends to be colder with minimum temperatures dipping to -10°C (15°F) and an average of 5°C (40°F), while March shows slightly milder conditions with a minimum of -8°C (17°F) and an average of 4°C (40°F). December experiences more significant precipitation, totaling 140 mm (5.5 in) over about 11 days, compared to March's 104 mm (4.1 in) over 10 days. Humidity levels remain fairly consistent, with December at 80% and March slightly higher at 81%. For a more detailed look at March weather, you can visit Port Jefferson weather in March.

In December, the weather is notably colder, with average temperatures hovering around 5°C (40°F) and nighttime lows dropping to -10°C (15°F). The month experiences significant precipitation, totaling 140 mm (5.5 in) over about 11 days, accompanied by high humidity levels around 80%. In contrast, April sees a milder climate, with average temperatures rising to 9°C (49°F) and maximums reaching 22°C (71°F). Despite a slightly lower total precipitation of 132 mm (5.2 in) across 12 days, the humidity is marginally lower at 78%. To learn more about the specific conditions in April, check out Port Jefferson weather in April.

In December, temperatures in Port Jefferson can drop to a minimum of -10°C (15°F), with average highs of around 5°C (40°F) and peaks reaching up to 17°C (62°F). The month sees a significant amount of precipitation, totaling 140 mm (5.5 in) over approximately 11 days, accompanied by high humidity levels of 80%. In contrast, May experiences more moderate temperatures, with a minimum of 3°C (37°F) and average highs of 14°C (58°F) to a maximum of 26°C (79°F). Although May does see some rain as well—119 mm (4.7 in) over about 13 days—the lower humidity of 69% contributes to a more pleasant atmosphere. For more detailed information, you can check Port Jefferson weather in May.

When comparing the weather in December and June, it becomes clear just how much the seasons differ. December experiences a chilly range of temperatures, with a minimum of -10°C (15°F) and an average around 5°C (40°F), peaking at 17°C (62°F). Precipitation is significant, totaling 140 mm (5.5 in) over 11 days, along with high humidity at 80%. In contrast, June brings much warmer conditions, with temperatures ranging from a minimum of 10°C (50°F) to an average of 20°C (68°F), reaching a maximum of 29°C (85°F). This month sees less precipitation, totaling 87 mm (3.4 in) over just 9 days, and a lower humidity level of 69%. For a detailed look at the weather patterns, you can refer to Port Jefferson weather in June.

December and July present strikingly different weather conditions. In December, temperatures can drop as low as -10°C (15°F) with an average of 5°C (40°F), while they peak at around 17°C (62°F). This month also sees higher humidity at 80% and 140 mm of precipitation over 11 days, contributing to a cold and often damp atmosphere. In contrast, July boasts significantly warmer temperatures, with a minimum of 16°C (60°F), an average of 24°C (76°F), and maximums reaching 33°C (91°F). Despite having slightly less precipitation at 131 mm over 12 days, July feels much drier with lower humidity at 62%. For a closer look at the specific conditions in July, you can check out Port Jefferson weather in July.

December and August exhibit stark contrasts in weather conditions. In December, temperatures can drop as low as -10°C (15°F) and typically average around 5°C (40°F), while maxing out at 17°C (62°F). The month sees considerable precipitation of 140 mm (5.5 in) over 11 days, accompanied by high humidity levels of 80%. In contrast, August boasts a more comfortable climate, with minimum temperatures at 16°C (61°F) and averaging 24°C (75°F), peaking at 31°C (88°F). Although August experiences some rain, with 103 mm (4.0 in) of precipitation over the same number of days, the humidity is significantly lower at 65%. For a deeper insight into August conditions, check Port Jefferson weather in August.

The weather in December is significantly colder compared to September, with temperatures ranging from a minimum of -10°C (15°F) to a maximum of 17°C (62°F) and an average of 5°C (40°F). In contrast, September enjoys milder temperatures, with a minimum of 11°C (52°F) and a maximum of 30°C (87°F), averaging around 21°C (70°F). Additionally, December experiences more precipitation at 140 mm (5.5 in) over 11 days, while September sees less at 94 mm (3.7 in) across 10 days. The humidity levels are also higher in December at 80%, compared to 68% in September. For more details about the weather in September, you can visit Port Jefferson weather in September.

December and October present contrasting weather patterns, with December experiencing much colder temperatures ranging from a minimum of -10°C (15°F) to a maximum of 17°C (62°F), while October boasts milder temperatures with lows of 5°C (41°F) and highs reaching 29°C (84°F). Both months feature similar precipitation levels, with December receiving 140 mm (5.5 in) over 11 days and October slightly higher at 143 mm (5.6 in) across 12 days. Humidity levels are also higher in December at 80%, compared to 74% in October, emphasizing the latter's warmer and drier conditions. For a detailed look at October's weather in Port Jefferson, you can visit Port Jefferson weather in October.

In comparing the weather of December and November, December experiences slightly colder temperatures, with a minimum of -10°C (15°F) and an average of 5°C (40°F), compared to November's minimum of -6°C (21°F) and average of 9°C (49°F). While both months have notable humidity, December shows a slightly lower average at 80% compared to November’s 82%. Precipitation also increases in December, totaling 140 mm (5.5 in) over 11 days, compared to November, which had 103 mm (4.0 in) over just 9 days. For a closer look at the specific conditions during November, you can visit Port Jefferson weather in November.

Compare Port Jefferson's Climate with Cities Worldwide

Conclusion: What to Expect From December Weather in Port Jefferson

As December settles in Port Jefferson, the weather takes a noticeable turn, characterized by cooler temperatures and increased humidity. The crisp chill permeates the air, with averages dipping significantly compared to the mild fall months, making it a true winter month. With an uptick in precipitation, residents see more rainy days that add to the wintry ambiance, contrasting sharply with the drier autumn. This shift creates a cozy atmosphere, perfect for the holiday season, and invites locals to embrace the unique charm of winter. To learn more about the overall climate patterns throughout the year, check out Port Jefferson Climate.