San Diego Weather in December: A Local's Guide

San Diego weather in December is mild but genuinely cool, the coolest and wettest month of the year, with warm-enough afternoons between storms, chilly nights, and the earliest sunsets of the entire year. We have lived here for 25 years, and December is a month we love for reasons that have nothing to do with the beach. The holiday season here is huge and mostly happens outdoors under string lights and clear-ish skies, gray whales start streaming past the coast, and the crowds are thin right up until the week between Christmas and New Year’s. You just have to come in with the right expectations, because it is not the endless-summer San Diego the postcards sell. Here is what to expect, broken down the way a local actually thinks about the month.

The short answer: December is San Diego’s coolest, wettest, and darkest month, and it is still pretty mild. Coastal highs average about 66 degrees and barely move, sliding from 67 early to 65 by New Year’s, with lows around 50. It is the wettest month, but wettest here means roughly 1.7 inches across about six rainy days, with sun in between. The ocean bottoms out at its yearly low, cooling from about 62 degrees to 60, so it is full-wetsuit water. The headline is the light: the earliest sunsets of the year land the first week of December, around 4:43 p.m., before creeping back to about 4:54 p.m. by December 31. Add the fullest events calendar of the year, the start of gray whale season, and thin pre-holiday crowds, and December is a great month to visit for everything except swimming.

How warm is San Diego in December?

At the coast, December is mild but cool, and it is San Diego’s coldest month of the year, if only by a hair. The average high is about 66 degrees and the average overnight low sits right around 50, and unlike most months, those numbers hardly budge from the first week to the last. Early December runs highs near 67 and lows around 52. By New Year’s you are looking at highs closer to 65 and lows near 50. Most days still climb comfortably past 60 in the afternoon sun, and a handful even reach the low 70s, so “coldest month” is very much relative here.

That mild average hides real day-to-day swing, though. A gray, rainy December day can top out in the upper 50s and feel raw, while a clear, calm one or a Santa Ana spike (more on that below) can push the coast into the low 70s and feel like a bonus summer afternoon. The nights are the part that surprises visitors: once the sun drops before 5 p.m., the temperature falls fast, and a 66-degree day becomes a 50-degree evening in a hurry. Locals dress in layers all month for exactly that reason.

Coast vs. inland vs. mountains vs. desert: the December spread

The most useful thing to understand about a San Diego December is that the county is really four climates at once, and the gap between them is at its widest this time of year. On the same afternoon, the coast can be a mild 66 while the mountains are near freezing and the desert is pleasant and dry. Cold air pools inland and up high at night, so the farther you get from the ocean, the colder the mornings.

Where you are	Dec average high	Dec average low	The reality
Immediate coast (beaches, La Jolla, Point Loma)	~66°F	~50°F	Mildest of all, rarely freezes, the warmest place to be after dark
Inland valleys (Escondido, El Cajon, Santee)	low-to-mid 60s	mid-to-high 40s	Similar days, noticeably colder nights, some frost in the coldest spots
Mountains (Julian, Laguna, Palomar)	low 50s at midday	30s, freezing nights	Genuinely cold, occasional snow up high, apple-country holiday charm
Desert (Borrego Springs, Anza-Borrego)	mid-60s	low-to-mid 40s	Dry and sunny by day, cold and clear at night, prime hiking and camping season

The practical takeaway is the same one we lean on all year: if you want more warmth, chase the sun inland or to the desert by day, and if the mountains sound too cold, stay near the water. December is a fantastic month up in Julian, the apple-country town in the Cuyamaca mountains, where the cold air, the pie shops, and the odd dusting of snow make it feel like a proper mountain Christmas an hour from the beach. When a storm drops snow on Mount Laguna or Palomar, San Diegans drive up the next morning to sled and throw snowballs, then come home to a 65-degree coast. It is one of the more absurd, wonderful things you can do here in a single winter day.

Does it rain in San Diego in December?

Yes, and December is San Diego’s single wettest month of the year. That still needs context, because wettest in San Diego is mild by almost any other city’s standard. The month averages about 1.7 inches of rain across roughly six rainy days, the heart of the wet season that runs November through March. The odds of a wet day climb steadily through the month, from around 12 percent on December 1 to about 17 percent by New Year’s Eve.

What that means for a trip is that most of December is still dry and usable, but the storms, when they come, are more serious than the light sprinkles of fall. A December storm can settle in for a full day of steady rain, sometimes back to back over a weekend, rather than the pass-through drizzle you get earlier in the season. Between systems, though, the skies clear right back up. San Diego is overcast or mostly cloudy a bit more than a third of December, its cloudiest share of the year, but that still leaves plenty of bright, clear afternoons. The move is simple: keep your outdoor plans flexible, watch the forecast the night before, and have a rainy-day backup ready. For where that gray comes from in the first place, and why summer and winter clouds are completely different beasts, see our explainer on June Gloom and the San Diego marine layer.

Is there a Santa Ana risk in December?

Yes, and December is actually one of the peak months for it. Santa Ana winds are the hot, dry gusts that blow offshore from the desert instead of the usual cool sea breeze, and San Diego’s Santa Ana season runs strongest through December, January, and February. When one lands in December, the pattern flips: the humidity crashes, the wind kicks up out of the east, and even the immediate coast can jump into the low 70s under a brilliant blue sky. It is the reason a “cold” month occasionally serves up a shorts-and-t-shirt afternoon.

The flip side is that those same warm, dry, windy conditions raise fire danger and can trigger precautionary power shutoffs in the backcountry, even this late in the year. Most Decembers see a Santa Ana or two pass without incident, and for a visitor it usually just means a gorgeous, unseasonably warm beach day dropped into the middle of your trip. If one is in the forecast, point yourself at the coast where it stays most comfortable, skip the exposed inland and mountain hikes that day, and enjoy the warmth while it lasts.

How warm is the ocean in December?

Cold, and this is the coldest the ocean gets all year. San Diego’s water temperature sits around 62 degrees at the start of December and eases down toward 60 by month’s end. That is firmly full-wetsuit territory for anything more than a quick, bracing dip. The surfers you see out at Ocean Beach, Pacific Beach, and Sunset Cliffs are in 4/3 wetsuits and often booties by now, and the year-round Cove swimmers who tough it out are a hardy exception, not the rule.

For a visitor, December is a month to use the ocean without getting all the way in. It is still excellent for tide pooling at low tide, which is genuinely at its best in winter, when the biggest daytime low tides of the year expose the reef in the afternoon. It is prime gray whale watching season starting mid-month, with boats running out of Point Loma as the whales migrate south to Baja. And it is fine for long beach walks and bonfires at the fire rings, which is how most locals use the sand in December anyway. If you do want to get in the water, an early-December warm spell or a Santa Ana day is your best window.

Sunset and daylight in December: the earliest sunsets of the year

Here is the single most counterintuitive thing December does to your day, and almost nobody expects it. The earliest sunset of the entire year in San Diego happens in the first week of December, not on the winter solstice. Around December 4, the sun drops at about 4:43 p.m., which is earlier than it sets on December 21. If you have ever wondered why it feels pitch dark so absurdly early right at the start of the month, that is why.

From that early-December low, the evenings quietly start getting lighter again, even as the total daylight keeps shrinking toward the solstice. Sunset climbs back to about 4:48 p.m. on the winter solstice, Monday, December 21, 2026, the shortest day of the year with about 10 hours and 3 minutes of daylight, and reaches roughly 4:54 p.m. by New Year’s Eve. Mornings move the opposite way to pay for it: sunrise slides later all month, from about 6:31 a.m. on December 1 to 6:49 a.m. on December 31, and the latest sunrises of the year do not arrive until early January. The whole month is standard time, since the clocks already fell back on November 1, so there is no jarring change like the one that surprises people in early November.

The practical effect is the same all month: plan your daylight around a hard 4:45 to 5 p.m. finish. Get your beach walk, tide pool, or hike done in the afternoon, and treat the long, dark evenings as the reason San Diego’s outdoor holiday lights work so well. For the full month-by-month rundown and our favorite places to catch it, see what time the sun sets in San Diego and our local ranking of the best sunset spots in San Diego. And since December hands you the longest nights of the year, they are also the best of the year for stargazing up in the mountains and desert.

What to pack for San Diego in December

Pack for mild days, cold nights, early darkness, and a real chance of rain. December asks more of your suitcase than any other San Diego month, because you genuinely need three registers of clothing.

• Daytime: jeans or pants, a t-shirt or light long sleeve with a sweater over it, and comfortable walking shoes. You will peel down to the base layer on a sunny afternoon and want the sweater back by 4 p.m.
• The evening layer: a proper jacket or a warm hoodie for after dark, when coastal nights fall to around 50 and the sun is gone before 5 p.m. This is the layer visitors most often leave at home and regret.
• A real rain layer: a packable waterproof jacket or a compact umbrella, because December is the wettest month and a storm can park over the county for a full day.
• Sun protection: the December UV index averages around 4, which is still “moderate,” so sunscreen and sunglasses earn their place on any clear midday, especially with the glare off the water.
• If you are heading to the mountains or desert: pack seriously warmer, with a heavy jacket, hat, and closed shoes. Julian and the backcountry drop below freezing at night in December and can get snow, and desert nights in Anza-Borrego get cold and clear.

December events worth planning around

December has the fullest events calendar of the whole year in San Diego, and most of it happens outdoors, which is exactly why the mild, mostly dry weather matters. Exact dates shift year to year, so confirm before you build a day around one, but here is the reliable lineup a local would point you to.

• Balboa Park December Nights. Usually the first Friday and Saturday of December, this is the city’s flagship free holiday festival and one of the largest in California, with dozens of performance stages, the international cottages serving food from around the world, a Friday tree lighting at the Spreckels Organ Pavilion, and, the true-local detail, many Balboa Park museums open free during the evening hours that weekend. It is the one weekend to museum-hop for nothing. Go early or take the trolley, because parking is a nightmare.
• Skating by the Sea at the Hotel del Coronado. An outdoor ice rink set up on the sand beside the historic Hotel del, running from roughly mid-November into early January. Skating in a t-shirt with the Pacific behind you is peak San Diego winter.
• San Diego Bay Parade of Lights. A parade of decorated boats that lights up San Diego Bay on two Sundays in December, usually starting around 5:30 p.m. It is free to watch from the waterfront, and Shelter Island, Harbor Island, Seaport Village, and the Coronado Ferry Landing are all good vantage points.
• Holiday lights across the county. Take your pick: Jungle Bells at the San Diego Zoo, Wild Holidays at the Safari Park up in Escondido, the SeaWorld Christmas Celebration on Mission Bay, and Winter Wonder at Belmont Park, the century-old beachfront amusement park in Mission Beach draped in over a million lights. Most are included with regular admission.
• Neighborhood lights and parades. Liberty Station in Point Loma lights its towering Norfolk pine and runs a seasonal ice rink, Seaport Village does nightly artificial snow flurries at 5 p.m. all month, Little Italy lights its tree and sets up a Christmas Village along India Street, and the La Jolla Christmas Parade and the quirky, beloved Ocean Beach Holiday Parade are both early-December local traditions worth catching.
• Gray whale season begins. The southbound gray whale migration starts passing San Diego mid-December and runs into April, with peak sightings in January and February. Whale-watching boats run out of the harbor off Point Loma.

Is it still beach weather in San Diego in December?

Yes and no, and the honest answer is what makes December worth it. It is not swimsuit weather, outside of a warm early-month afternoon or a Santa Ana spike. But it is absolutely beach weather in the way locals actually use the coast in winter: bundled-up walks on empty sand, bonfires at the fire rings as the early dark comes in, tide pooling at the best low tides of the year, whale watching, and catching a sunset that now conveniently happens before dinner. The beaches are nearly empty until the holidays, the light off the water is gorgeous, and you never fight for parking. Bring a jacket for after the sun drops and December gives you some of the most peaceful beach days of the entire year.

The trap to skip

The classic December mistake is coming for a beach vacation and being blindsided by the reality. Visitors book December expecting warm water and long sunny evenings, then find a 60-degree ocean, a 4:45 p.m. sunset, and the chance of a rainy day, and they leave disappointed. The fix is a mindset shift, not a different city: come to San Diego in December for the holidays, the whales, the mild hiking weather, and the empty off-season beaches, and treat any warm swimmable afternoon as a bonus. Framed that way, it is one of the best-value months of the year to be here.

The second trap is not respecting the mountains. Every December, someone drives up to Julian or Mount Laguna in shorts to see the snow, gets caught out by freezing temperatures or an icy road, and has a miserable afternoon. If you are heading up the hill, pack real winter clothes, check road conditions after a storm, and remember that “San Diego” and “near freezing” are both true on the same day, just an hour apart.

Planning the rest of your December trip

A rainy December day or an early sunset is the perfect excuse to line up something indoors and weather-proof. A hotel with an indoor or heated pool is about the most storm-proof place in the city, and worth booking if you are here across a wet stretch. It is also worth seeing how December stacks up against the shoulder months right before it, so compare it with our guides to San Diego weather in November and San Diego weather in October. And if a cold snap has you wondering just how low it goes, our piece on whether it snows in San Diego covers the mountains that get a December dusting.

For booking a December stay, whether you want a beachfront room for the holidays or a mountain cabin near the Julian lights, browse the travel and lodging category in our San Diego business directory. And for the month’s parades, light shows, whale-watching trips, and rainy-day backups, the entertainment and recreation category is the place to start.