December Weather in San Francisco, United States

Last updated: February 24, 2025

December in San Francisco offers a cool yet inviting climate, with temperatures ranging from a minimum of 4°C (40°F) to a maximum of 20°C (69°F). The average temperature settles at a comfortable 11°C (52°F), creating ideal conditions for outdoor exploration. However, this month also brings moderate rainfall, accumulating to 95 mm (3.7 in) over approximately 9 rainy days, adding a refreshing touch to the city’s vibrant atmosphere. With a humidity level of 79%, the air feels crisp and invigorating, making December a unique time to experience the charm of San Francisco.

December Temperature in San Francisco

In December, San Francisco experiences mild temperatures that reflect a subtle transition towards cooler winter months. With minimums of 4°C (40°F) and maximums around 20°C (69°F), the weather remains relatively comfortable, averaging 11°C (52°F). This pattern continues the trend of winter temperatures that are consistently warmer compared to many other regions, with no dramatic dips, as seen in the previous months. As the year wraps up, the city's climate remains inviting, encouraging locals and visitors alike to explore its iconic streets, albeit with a light jacket in tow. The mild December conditions exemplify San Francisco's unique climate, where chilly winds often give way to sunny afternoons, making for a delightful end to the year.

December Weather in San Francisco: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in San Francisco, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec515253555659596162605552
Data source: Temperature data for San Francisco 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 San Francisco

December in San Francisco marks a notable transition in the city's weather patterns as precipitation levels rise, contributing to the overall wet season. With an average rainfall of 95 mm (3.7 in) over 9 days, December showcases a significant increase compared to the drier summer months, where the city experiences little to no rain. This late fall surge in moisture not only blankets the city in lush greenery but also sets the stage for the wetter months ahead, as January and February follow closely with similar precipitation levels. The trend indicates a clear shift from the previous months' minimal rain, emphasizing the importance of December in replenishing the urban landscape before the new year.

December Precipitation Trends in San Francisco

The chart displays monthly precipitation patterns in San Francisco, 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.
JanFebMarAprMayJunJulAugSepOctNovDec1061097835203322305095
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in San Francisco

As December arrives in San Francisco, the city enjoys a refreshing drop in humidity, settling at 79%. This level mirrors the lower humidity typically seen in November, marking the transition to a drier winter spell. Throughout the year, humidity levels fluctuate, peaking in the summer months of July and August at an elevated 87%, while the early part of the year tends to maintain a higher average around 81% to 85%. The consistent decline from early autumn to the end of the year signals a gradual shift in the coastal climate, providing residents and visitors a more refreshing, crisp atmosphere during the holiday season.

December Average Humidity in San Francisco

This chart illustrates the average monthly humidity levels in San Francisco, 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.
JanFebMarAprMayJunJulAugSepOctNovDec85%82%82%79%83%84%87%87%86%80%79%79%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in San Francisco

As December rolls into San Francisco, the UV Index dips back to a moderate level of 3, similar to January and November. During this month, residents and visitors can expect a burn time of around 30 minutes without adequate protection. This trend reflects a seasonal shift where the intensity of UV radiation decreases, contrasting starkly with the peak summer months when the index soared to extremes of 11 in June and July. The transition from the intense solar exposure of late spring and summer to the milder conditions in December reminds us to remain vigilant about sun safety year-round, even in cooler months. For detailed information on UV levels throughout the year, check out San Francisco UV Index.

Maximum UV Index Levels in San Francisco for December

The chart shows the monthly maximum UV Index (UVI) for San Francisco 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.
JanFebMarAprMayJunJulAugSepOctNovDec3589101111109743
Data source: San Francisco 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 San Francisco

In December, San Francisco experiences a distinct transition as daylight begins to wane, offering 194 hours of sunshine. While this marks a dip from the peak brightness of June at a vibrant 355 hours, it's essential to appreciate that December still enjoys more sunshine than its early winter counterparts, like January, with only 151 hours. Interestingly, the city sees a gradual decline from the abundant light of summer, where sunshine averages around 320 hours in August, down to the year's dimmest month. As the year wraps up, while sunshine may be less plentiful, San Francisco's charm remains radiant, inviting residents and visitors alike to embrace the beauty of its crisp winter days.

Monthly Sunshine Duration in San Francisco: December Highlighted

The December sunshine duration represents the total number of hours San Francisco 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.
JanFebMarAprMayJunJulAugSepOctNovDec151h216h263h296h341h355h349h320h299h276h225h194h
Data source: San Francisco December Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in San Francisco During December

As December rolls into San Francisco, residents and visitors should brace themselves for the least sunny month of the year, with a modest 33% chance of basking in the sun's rays. This decline in sunny weather is part of a broader trend as we transition from the brighter months of late spring and early summer. Notably, December's sun probability is significantly lower than the peaks seen in May and March, which boast 66% and 62% chances, respectively. With the city’s summer months also dimming, illustrating a typical pattern of variability, December often presents a mix of cool temperatures and overcast skies, reminding us that San Francisco's charm persists beyond its sunny days.

Percentage of Sunny Days in December in San Francisco

The chart illustrates the percentage of sunny days in San Francisco 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 San Francisco experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec39%56%62%56%66%51%37%47%51%51%42%33%
Data source: San Francisco December chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in San Francisco in December

In December, San Francisco experiences a return to shorter days, with daylight lasting about 9 hours. This marks the culmination of the year’s gradual decline in sunlight that begins in June, when the city enjoys up to 14 hours of daylight. Following the peak of summer, daily sunlight decreases steadily through the fall months, reaching its nadir in December. The transition from November's 10 hours to December's 9 highlights a rhythmic pattern of day length that mirrors the changing seasons. As the city ushers in winter, residents are reminded of the cozy, reflective evenings that accompany the shortest days of the year.

Average Daylight Hours in San Francisco for December

The chart illustrates the variation in daylight duration in San Francisco throughout the year, with December highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 53m10h 48m11h 59m13h 11m14h 12m14h 42m14h 26m13h 31m12h 22m11h 9m10h 7m9h 35m
Data source: San Francisco daylight hours, calculated by summing the hours between sunrise and sunset for each day.

December Winds in San Francisco

As December settles in San Francisco, the average wind speed reaches a brisk 3.9 m/s (9 mph), reflecting a subtle increase compared to the calmer months leading up to it. The winds of late fall, which dipped to a gentle 2.7 m/s (6 mph) in November, gradually build up as winter approaches, signaling a shift in the coastal climate. This uptick in wind speed is part of a broader seasonal trend, where spring and early summer months showcase the strongest breezes, peaking at 5.4 m/s (12 mph) in May. A dynamic patient follows through the year, characterized by a gradual decline into the quieter days of autumn. Thus, while December may not boast the highest gusts, it certainly serves as a reminder that even in cooler months, the winds of San Francisco are a constant companion.

Average December Wind Speed in San Francisco

The chart displays monthly wind speed patterns in San Francisco, 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.
JanFebMarAprMayJunJulAugSepOctNovDec3.24.04.14.65.44.74.03.73.33.72.73.9 m/s
Data source: San Francisco December wind data, generated using information from the Copernicus Climate Change Service.

How December Weather in San Francisco Compares to Other Months

The weather in San Francisco 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 San Francisco and find detailed weather information for every month.

December and January share similar average temperatures, with December experiencing a minimum of 4°C (40°F) and a maximum of 20°C (69°F), while January sees slightly cooler nights with a minimum of 3°C (38°F) and a peak of 21°C (70°F). Both months have an average temperature of 11°C (52°F), but January tends to be slightly wetter, with 106 mm (4.2 in) of precipitation compared to December's 95 mm (3.7 in), although both months register precipitation on about 9 days. Additionally, January has a higher humidity level at 85%, compared to December’s 79%, making the start of the year feel a bit wetter overall. For more detailed information, you can check out San Francisco weather in January.

In comparing the weather between December and February, we find that both months experience a similar temperature range, with minimums around 4°C (40°F), averages at 11°C (52°F), and maximums reaching up to 20°C (69°F). However, February tends to be a bit wetter, with total precipitation at 109 mm (4.3 in) compared to December’s 95 mm (3.7 in), despite both months having about 9 days of rainfall. Additionally, February's humidity is slightly higher at 82% versus December's 79%. For a more detailed look at climate specifics, check out San Francisco weather in February.

In December, temperatures in San Francisco range from a minimum of 4°C (40°F) to a maximum of 20°C (69°F), with an average temperature of 11°C (52°F). The month experiences about 95 mm (3.7 in) of precipitation over approximately 9 days, and humidity levels are around 79%. In contrast, March sees slightly higher temperatures, with a minimum of 5°C (42°F) and an average of 12°C (53°F), maintaining the same maximum of 20°C (69°F). Rainfall in March is lower, totaling 78 mm (3.1 in) over about 10 days, with a slightly higher humidity of 82%. For a more detailed look at typical weather patterns, you can explore San Francisco weather in March.

In December, the weather is cooler, with temperatures ranging from a minimum of 4°C (40°F) to a maximum of 20°C (69°F), resulting in an average of 11°C (52°F). This month also experiences higher precipitation, totaling 95 mm (3.7 in) over 9 days, while maintaining a consistent humidity level of 79%. In contrast, April brings milder temperatures, with a minimum of 7°C (44°F) and a maximum reaching 28°C (82°F), leading to an average of 13°C (55°F). Rainfall is significantly reduced to 35 mm (1.4 in) across just 5 days, yet the humidity remains at 79%. For more detailed insights into the specific conditions, check out San Francisco weather in April.

In December, the weather is generally cooler, with temperatures ranging from a minimum of 4°C (40°F) to a maximum of 20°C (69°F) and an average of 11°C (52°F). This month also sees considerable precipitation, with about 95 mm (3.7 in) falling over approximately 9 days, contributing to a humidity level of 79%. In contrast, May experiences milder temperatures, with a minimum of 8°C (47°F) and a maximum of 24°C (75°F), averaging around 14°C (57°F). Rainfall significantly decreases during May, totaling only 20 mm (0.8 in) over just 2 days, and the humidity climbs slightly to 83%. For a detailed overview of weather patterns, visit San Francisco weather in May.

When comparing the weather in December and June, we see a notable difference in temperature and precipitation. December features cooler temperatures, with a minimum of 4°C (40°F) and a maximum of 20°C (69°F), while June enjoys a warmer range, with temperatures ranging from a minimum of 10°C (51°F) to a maximum of 31°C (88°F). Precipitation is much heavier in December, averaging 95 mm (3.7 in) over about 9 days, compared to June, which is typically dry with just 3 mm (0.1 in) of rain and no rainy days. Humidity levels are somewhat similar, with December at 79% and June slightly higher at 84%. For those interested in the specifics of June weather, you can check out San Francisco weather in June.

December and July in San Francisco present stark contrasts in weather conditions. In December, temperatures range from a minimum of 4°C (40°F) to a maximum of 20°C (69°F), with an average of 11°C (52°F). This month also sees significant precipitation, totaling 95 mm (3.7 in) over about 9 days, coupled with a humidity level of 79%. In contrast, July features milder temperatures with a minimum of 11°C (52°F) and a maximum of 24°C (76°F), averaging 15°C (60°F). Precipitation is minimal in July, with only 3 mm (0.1 in) and no rainy days, highlighting a much drier atmosphere despite slightly higher humidity at 87%. For more detailed information, check out San Francisco weather in July.

In December, temperatures in San Francisco range from a minimum of 4°C (40°F) to a maximum of 20°C (69°F), with an average of 11°C (52°F). The month sees significant rainfall, totaling 95 mm (3.7 in) over about 9 days, and humidity levels hover around 79%. In contrast, August experiences a milder climate, with temperatures varying from a minimum of 11°C (53°F) to a maximum of 27°C (81°F) and an average of 16°C (61°F). Remarkably, August is characterized by very little precipitation, receiving only 2 mm (0.1 in) on no rainy days, and slightly higher humidity at 87%. For more detailed insights, check out San Francisco weather in August.

The weather in December is notably cooler than in September, with average temperatures ranging from a minimum of 4°C (40°F) to a maximum of 20°C (69°F), compared to September's warmer averages of 11°C (51°F) to 35°C (96°F). Additionally, December is marked by increased precipitation, receiving about 95 mm (3.7 in) over nine days, while September boasts a dry climate with just 2 mm (0.1 in) of rain, occurring over no days. Humidity levels are slightly higher in September at 86%, compared to December's 79%. For more details about September’s weather, check out San Francisco weather in September.

In comparing the weather between October and December, notable differences emerge. October typically boasts warmer temperatures, with an average of 16°C (60°F), while December sees a cooler average of 11°C (52°F). Additionally, October often features maximum temperatures reaching up to 28°C (84°F), compared to December's peak of 20°C (69°F). Precipitation also varies significantly; October experiences just 30 mm (1.2 in) of rain over 2 days, while December is considerably wetter, accumulating 95 mm (3.7 in) over 9 days. Humidity levels remain relatively consistent, with October at 80% and December slightly lower at 79%. For more details on October weather, you can visit San Francisco weather in October.

When comparing the weather in December to November, we can observe a slight dip in temperatures and an increase in precipitation. December has a minimum temperature of 4°C (40°F) and an average of 11°C (52°F), while November is slightly warmer with a minimum of 6°C (43°F) and an average of 13°C (56°F). Additionally, December experiences more rainfall, with 95 mm (3.7 in) over 9 days, compared to November's 50 mm (2.0 in) over 5 days. Interestingly, both months maintain a consistent humidity level of 79%. For a more detailed look at November's weather, you can visit San Francisco weather in November.

Compare San Francisco's Climate with Cities Worldwide

Conclusion: What to Expect From December Weather in San Francisco

As December sweeps into San Francisco, it brings a refreshing change from the relatively dry and warmer months. The city experiences cooler temperatures, with mild afternoons contrasting against brisk evenings. While average humidity remains high, the increase in precipitation signals the arrival of winter storms, resulting in a wetter atmosphere compared to previous months. This blend of cool weather and rain enhances the city's iconic charm, making it a unique time to explore. For further insights on the city's weather patterns throughout the year, visit San Francisco Climate.