December in LA: What Actually Happens and How to Prepare
Most people assume Los Angeles is sunny and warm year-round. It isn't. December is genuinely the start of the wet season, and the temperature swings can be jarring if you're not ready for them. I spent about seven years managing outdoor event logistics in the area before moving away, and the number one mistake I saw people make was underestimating how cold it gets after sunset. Not freezing, but cool enough that a t-shirt and jacket combo is the standard uniform, not a one-layer outfit. The average high sits around 68°F (20°C) and the average low hovers near 50°F (10°C). That's the textbook number, and it's roughly accurate for downtown and the basin. If you're in the mountains or the Antelope Valley, it's five to ten degrees colder. If you're right on the coast near Santa Monica or Malibu, it might stay in the mid-50s at night and barely crack 65 during the day. The ocean has a real moderating effect that inland areas don't get.
Weather Los Angeles California December Average Temperatures Rainfall And What To Expect
Rainfall in December averages about 2.8 inches across the LA basin. That sounds small until you realize most of it comes in three or four events. It doesn't drizzle for weeks. It usually dumps hard for a few hours, sometimes a full day, and then clears out. I remember one December back in 2016 when an atmospheric river hit and dumped nearly an inch in under two hours on the 405. Traffic was paralyzed for four hours because nobody in this city is built for rain. The drainage infrastructure in a lot of neighborhoods is ancient, and standing water shows up within minutes on surfaces that stay bone-dry the rest of the month. The workaround I ended up using was checking radar every morning on RadarScope, not the generic weather app. The forecast model would say light rain in the afternoon, but the real-time reflectivity showed a cell moving in from the Channel Islands that the model had missed. You learn pretty quickly that the official daily rainfall total is almost always lower than what actually falls at your specific location. The gauges are spaced far apart, and convective winter showers don't cover wide areas. There's also the Santa Ana wind phenomenon to think about. Around mid-December some years, you'll get a stretch where the northeasterly winds push through the canyons and the temperature actually spikes to 75 or 80 degrees with single-digit humidity. That happened for about five days straight in December 2019. It's dry, it's windy, and it makes everything a fire risk. The last time I managed events during a Santa Ana event, the dust and wind made outdoor setups nearly impossible. Canvas tents became sails, and the static buildup on equipment was annoying. I learned to just shift everything indoors or delay by 24 hours. The wind doesn't care about your schedule.
If you're visiting or relocating and trying to figure out what to pack, here's the practical truth. Layering is the answer. A light long-sleeve shirt, a fleece or medium sweater, and a windbreaker or light jacket covers basically every scenario you'll hit. Umbrella yes, but don't overpack for rain gear. Heavy rain gear sits unused most of the month. Sunglasses still matter because even cloudy December days in LA have significant UV, especially if you're near the beach where the reflection doubles your exposure. One thing that catches people off guard is the dawn timing. Sunrise in early December is around 6:50 AM and sunset is about 4:45 PM. By the time you leave work at five, it's already dark. If you're used to southern California's reputation for long sunny evenings, December shuts that down completely. The short days affect everything from restaurant reservations to traffic patterns. People get out earlier and the evening commute feels compressed into an hour of actual darkness instead of the extended golden-hour commute you get in summer. The ocean is cold. About 58 to 60 degrees Fahrenheit along the main beaches. I know surfers who'll tell you otherwise, but for anyone not wearing a wetsuit, it's cold enough that a quick dip is refreshing and then you're shivering for twenty minutes. The beach is still walkable and nice in the afternoon sun, but swimming is a commitment most visitors aren't prepared for.
Get the Full Details
There's a common assumption that December means holiday decorations everywhere. That's mostly true in the central and western parts of the city, but a lot of the valley neighborhoods and the eastern areas don't do much decorating. If you're driving through from the Harbor area up through the 405 corridor, you'll see the usual light displays. Head east on the 60 or out toward San Gabriel and the whole vibe changes. Nothing wrong with that, just set your expectations accordingly. For someone planning a trip or trying to decide whether to move somewhere in the LA basin, December is probably the least dramatic month weather-wise. It's not summer dry heat. It's not a true winter with snow or sustained cold. It's a transition period that sits somewhere between Mediterranean and temperate rain forest depending on where you are. The temperature range is manageable. The rain is sporadic. The biggest adjustment is just getting used to the shorter days and the fact that the city doesn't slow down because the weather changes.
