Los Angeles December Weather: The Complete Guide to Temperatures, Rainfall, and What to Pack
December in Los Angeles marks the definitive transition from dry, fire-season anxieties to the beginning of the region’s wet season. While the city does not experience the extreme cold or snow common to other parts of the nation, this month introduces a sharper chill and a higher likelihood of storm systems rolling in from the Pacific. This guide provides a detailed breakdown of temperatures, precipitation patterns, ocean conditions, and expert advice for navigating the unique weather characteristics of the City of Angels during the winter month of December.
The Temperature Paradox: Sunshine vs. The Chill
One of the most defining features of Los Angeles weather in December is the significant temperature variation between direct sunlight and shade, as well as between the coast and the inland valleys and mountains. The city rarely experiences freezing temperatures at sea level, but the perceived cold can be biting due to wind chill and humidity. Understanding this microclimatic diversity is essential for avoiding discomfort during the month.
Coastal and Downtown Areas
The urban core and coastal zones benefit from the moderating influence of the Pacific Ocean. Daytime highs typically range from the upper 60s to low 70s Fahrenheit (18-23°C). However, due to the winter sun angle and frequent marine layers, the "feels-like" temperature can often be cooler than the thermometer indicates. Morning and evening temperatures frequently dip into the low 50s Fahrenheit (10-12°C), requiring a jacket even in areas like Santa Monica or Venice Beach.
Inland Valleys and Suburbs
Just a few miles inland, the climate shifts dramatically. Areas such as the San Fernando Valley, Burbank, and Glendale experience more continental influences, leading to more extreme daily swings. It is common for these regions to see daytime temperatures reach a pleasant 70°F (21°C) under clear skies, only to drop to a crisp 40°F (4°C) or lower after sunset. This phenomenon makes layering a critical strategy for residents and visitors alike.
Mountain Regions
For those visiting or living in the San Gabriel Mountains or the Santa Monica Mountains, December brings a true winter experience. While snow is rare at the very peaks of the Angeles National Forest, it is not unheard of. Communities like Big Bear Lake or the higher elevations of Malibu will see regular frost and temperatures consistently below 40°F (4°C), creating a landscape often dusted with white and popular for holiday skiing.
Rainfall and Atmospheric Rivers
December is statistically the wettest month of the year in Los Angeles. The dry season that characterized the summer and early fall comes to an end as the jet stream shifts southward, allowing Pacific storm systems to impact Southern California. While rain can fall in November, December is when the city’s water budget is often filled.
The "Pineapple Express" Factor
A recurring feature of Southern California winter weather is the "Pineapple Express." This meteorological term refers to a narrow corridor of moisture that taps into the tropical waters near Hawaii and directs it straight toward the West Coast. When this plume of warm, moist air collides with the cooler California atmosphere, it results in intense, albeit often brief, periods of heavy rainfall.
Monthly Averages and Extremes
On average, Los Angeles sees approximately 3 to 4 inches of rain in December. However, this figure masks the volatility of the season. Some Decembers pass with barely a drop, while others, influenced by successive atmospheric rivers, can produce flooding conditions. Historically, the month has produced the highest single-day rainfall totals of the year, making it a critical period for water management and urban drainage systems.
- Typical Rainy Days: 3-5 days with measurable precipitation.
- Average Rainfall: 3.02 inches (76.7 mm).
- Record High: 88°F (31°C) set in 1975.
- Record Low: 24°F (-4°C) set in 1962.
Ocean, Wind, and Humidity
The Pacific Ocean remains cold throughout December, with average water temperatures hovering around 58°F (14°C). This cold water has a direct impact on the coastal climate, keeping offshore breezes cool and preventing the coastal areas from warming up significantly during the day.
Wind Patterns
Santa Ana winds, while more famous in the fall, can still occur in December. These winds originate in the high desert and mountain areas, blowing hot, dry air through the coastal mountain passes and into the urban basins. When Santa Ana winds occur in December, they can rapidly increase temperatures in the inland valleys by 10–20 degrees and create critical fire weather conditions, despite the general wetness of the month.
Humidity and Dew Points
The humidity in Los Angeles during December is generally moderate. However, during the passage of a storm system, humidity levels spike, creating a damp, penetrating cold that affects the bones. Conversely, the clear days following a storm system often feature very low humidity and exceptionally crisp air, providing some of the clearest views of the region’s topography.What to Pack and How to Prepare
Visiting or surviving a Los Angeles December requires a strategic approach to packing. The era of wearing only light linen is over; the season demands a mix of textures and weights to navigate the daily volatility.
The Essential Winter Kit
- Layering Pieces: Forget the heavy winter coat. Opt for a medium-weight bomber jacket or a wool car coat. This allows you to add or remove layers as you move between the warm interior of a coffee shop and the chilly outdoor air.
- Bottoms: Bring a mix of jeans (heavier denim is fine) and perhaps a pair of corduroys or thick cotton trousers for evenings.
- Footwear: Waterproof boots or sneakers are a necessity. The city’s infrastructure, while advanced, can struggle during sudden downpours, leading to puddles on sidewalks.
- Accessories: A compact umbrella is highly recommended. Additionally, a scarf and a pair of gloves are useful for early morning walks or evenings on the pier, even if you don’t use them all day.
Outdoor Activities
Hiking remains a popular activity in December, but conditions can change rapidly. Trails that are dusty and dry in November may be muddy and slick by mid-month. It is advisable to check trail conditions on platforms like AllTrails or the National Forest Service website before embarking on a hike. Furthermore, beaches, while less crowded, are often windy and cold, making them better suited for brief walks than for sunbathing.
The Meteorological Outlook
Looking ahead, the long-range models suggest that the current atmospheric pattern favoring the jet stream toward the West Coast may persist through much of the season. This suggests that December 2024 is likely to follow the historical average for precipitation, leaning toward the wetter side of the spectrum. Climate scientists note that while individual weather events cannot be directly attributed to climate change, the frequency of extreme atmospheric river events aligning with warmer ocean temperatures is a trend being monitored closely.
For the residents of Los Angeles, December is a month of duality. It is a time of vibrant holiday lights and gatherings, juxtaposed with the raw power of the Pacific storms. It is a reminder that even in a city known for its perpetual summer, the wheel of the year turns, and winter, in its own distinct and dramatic way, arrives.
