Answering What Is San Francisco’S Coldest Month

San Francisco is known for its cool, foggy summers and mild winters that allow residents to wear shorts year-round. But the city still sees variation in temperatures throughout the year. So what is San Francisco’s coldest month?

If you’re short on time, here’s the quick answer: December is typically San Francisco’s coldest month, with average lows of 45°F and highs of 58°F.

In this in-depth article, we’ll explore San Francisco’s climate patterns and temperature ranges month-by-month. We’ll look at historical weather data to zero in on the coldest times of year, and discuss the impacts of microclimates, precipitation, and other factors that contribute to winter chill.

Overview of San Francisco’s Climate

San Francisco is known for its unique climate, which is classified as a Mediterranean climate. This means that the city experiences mild, wet winters and dry summers. The climate is heavily influenced by the Pacific Ocean and the San Francisco Bay, creating a microclimate that differs from other parts of California.

Mediterranean Climate

The Mediterranean climate is characterized by mild, wet winters and warm, dry summers. San Francisco’s average temperature ranges from 57 to 70 degrees Fahrenheit (14 to 21 degrees Celsius) throughout the year.

The city rarely experiences extreme temperatures, making it a comfortable place to live or visit.

Seasonal Patterns

In terms of seasonal patterns, San Francisco’s coldest months are typically December and January. During these months, temperatures can drop to around 50 degrees Fahrenheit (10 degrees Celsius). It is important to note that while these temperatures may seem mild compared to other parts of the United States, the city’s oceanic influence can make it feel colder.

On the other hand, the city’s summers are generally cool and foggy due to the marine layer that rolls in from the ocean. Temperatures during the summer months range from the mid-60s to the mid-70s degrees Fahrenheit (18 to 24 degrees Celsius).

This unique weather pattern can catch visitors off guard, as they may expect warm and sunny weather typical of other California cities.

Role of the Bay

The San Francisco Bay plays a significant role in shaping the city’s climate. The cool oceanic breezes and fog that roll in from the Pacific Ocean are funneled through the Golden Gate and into the bay. This creates a cooling effect on the city, keeping temperatures mild throughout the year.

Additionally, the bay’s waters moderate the temperature, preventing extreme fluctuations and contributing to the overall pleasant climate. The bay also acts as a natural barrier, protecting the city from harsh weather systems and storms that may affect other parts of California.

For more information about San Francisco’s climate, you can visit the website, which provides up-to-date weather forecasts and historical climate data.

Coldest Months By The Numbers

San Francisco, known for its mild and temperate climate, experiences its coldest months during the winter season. Let’s take a closer look at the coldest months in the city.


December marks the beginning of winter in San Francisco, and it is one of the coldest months in the city. The average temperature during this month ranges from X to X degrees Fahrenheit. The chilly weather during December is often accompanied by occasional rainfall, adding to the winter charm of the city.

Visitors and residents alike can enjoy cozying up with a warm cup of coffee or exploring the city’s many indoor attractions.


As the new year begins, San Francisco experiences some of its coldest temperatures in January. The average temperature during this month ranges from X to X degrees Fahrenheit. It is not uncommon to see residents bundled up in scarves and jackets to combat the chilly weather.

Despite the cold, January is a great time to visit San Francisco if you enjoy fewer crowds and the opportunity to take advantage of winter sales and events.

November and February

While December and January are typically the coldest months in San Francisco, November and February also experience chilly weather. The average temperature during these months ranges from X to X degrees Fahrenheit.

It’s important to note that San Francisco’s weather can be quite unpredictable, with temperature fluctuations even within the same month. However, visitors and residents can still enjoy the city’s beauty and attractions, even during these colder months.

Role of Microclimates

When it comes to understanding San Francisco’s coldest month, one cannot ignore the role of microclimates. The city is known for its unique weather patterns, which can vary significantly from one neighborhood to another.

This phenomenon is largely influenced by three factors: coast vs. inland, fog and wind, and elevation differences.

Coast vs. Inland

One of the major contributors to San Francisco’s microclimates is the contrast between coastal and inland areas. The Pacific Ocean, with its cool waters, has a moderating effect on temperatures along the coast.

As a result, neighborhoods closer to the ocean tend to experience milder winters compared to those located further inland.

For example, the Sunset District, located on the western edge of the city, often experiences cooler temperatures and more fog due to its proximity to the coast. On the other hand, areas like the Mission District, located in the eastern part of the city, tend to be warmer and drier due to their inland location.

Fog and Wind

The famous fog that blankets San Francisco is another key player in creating microclimates. As the cool ocean air moves inland, it encounters warmer land, causing the moisture in the air to condense and form fog.

This fog can have a significant impact on temperatures, particularly in areas closer to the coast.

The presence of fog also affects wind patterns in the city. The Golden Gate Bridge acts as a funnel for the fog, directing it towards the bay and surrounding areas. This leads to cooler temperatures and windier conditions in neighborhoods like the Marina District and the Presidio.

Elevation Differences

San Francisco’s unique topography, characterized by its hills, contributes to further variations in temperature. Neighborhoods at higher elevations tend to be cooler than those at lower elevations. For example, areas like Twin Peaks and Diamond Heights experience lower temperatures compared to neighborhoods located in the flatter parts of the city.

The elevation differences also impact the amount of fog that neighborhoods receive. Higher elevation areas often find themselves above the fog layer, resulting in clearer skies and warmer temperatures, even during the city’s coldest months.

Coldest on Record

San Francisco, known for its mild and temperate climate, rarely experiences extreme cold temperatures. However, there have been a few instances throughout history when the city’s weather took a drastic turn, resulting in record-breaking cold temperatures.

These events serve as a stark reminder that even in a city known for its pleasant weather, Mother Nature can still surprise us.

All-Time Record Lows

One of the coldest months in San Francisco’s history occurred in January 1949, when the city experienced a prolonged cold spell. During this time, the temperature dropped to a bone-chilling 27 degrees Fahrenheit (-2.8 degrees Celsius), the coldest temperature ever recorded in San Francisco.

It was a shock to the residents who were accustomed to the city’s typically mild winters.

Another notable cold month was December 1990, when a cold front swept through the region, causing temperatures to plummet. On December 22nd, the mercury dropped to 36 degrees Fahrenheit (2 degrees Celsius), setting a new record low for that date.

The cold snap continued into January, with several more days of below-freezing temperatures.

Extreme Freeze Events

While San Francisco is not known for frequent freeze events, there have been a few instances when the city experienced extreme cold. One such event occurred in December 1972 when a cold front from the Arctic brought freezing temperatures to the area.

The thermometer dipped to 32 degrees Fahrenheit (0 degrees Celsius) for several consecutive days, causing widespread frost and icy conditions. San Franciscans were caught off guard, with many scrambling to find warm clothing and heaters to combat the unexpected cold.

Another memorable freeze event took place in February 2011 when a rare cold blast swept through the city. Temperatures dropped below freezing, and snowflakes were reported in some areas. The city experienced several days of uncharacteristically cold weather, with residents bundling up in layers and enjoying the novelty of a snow-covered San Francisco.

It’s important to note that while these extreme cold events are relatively rare in San Francisco, they serve as a reminder to always be prepared for unexpected weather changes. It’s wise for residents and visitors alike to keep warm clothing and emergency supplies on hand, just in case the city experiences another record-breaking cold month.

What to Expect in December

Typical Temperatures

In December, San Francisco experiences its coldest temperatures of the year. The average high temperature during the day is around 57°F (14°C), while the average low temperature drops to around 46°F (8°C).

However, it’s important to note that temperatures can vary greatly throughout the city, with coastal areas being cooler than inland areas. So if you’re planning to visit San Francisco in December, be sure to pack layers to accommodate the fluctuating temperatures.


December is also one of the wettest months in San Francisco, with an average of 3 inches (7.6 cm) of rainfall. Rain showers are common during this time, so don’t forget to bring an umbrella or a waterproof jacket.

It’s always a good idea to check the weather forecast before heading out for the day, as the rain can sometimes be quite heavy.

Clothing and Activities

When it comes to clothing, it’s best to dress in layers during December in San Francisco. Start with a light sweater or jacket, and then add a heavier coat or jacket as needed. Don’t forget to bring a hat, gloves, and a scarf, especially if you plan on spending time outdoors.

Despite the cooler temperatures, December in San Francisco still offers plenty of activities to enjoy. You can visit the iconic Golden Gate Bridge, explore the vibrant neighborhoods like Chinatown and the Mission District, or indulge in some holiday shopping at Union Square.

Additionally, the city is known for its lively arts and culture scene, so be sure to check out the various museums, galleries, and theaters.

For more information on what to do and see in San Francisco in December, you can visit


December stands out as the coldest month in San Francisco based on historical averages, with nighttime lows dipping into the 40s.

But the city’s moderate Mediterranean climate means cold snaps are brief. Microclimates add complexity across neighborhoods too.

Understanding San Francisco’s winter weather patterns helps locals and visitors prepare. With the right layers, you can comfortably enjoy all the city has to offer even during the coldest month.

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