San Diego Weather in December: Temperatures, Rain and Packing

San Diego weather in December: the short answer

December in San Diego is mild, mostly dry and short on daylight. Based on NOAA’s 1991–2020 climate normals for San Diego International Airport (Lindbergh Field), the average December high is 66.0°F and the average low is 49.8°F. Rain falls on only a handful of days, and most of the month is dry.

The catch is the evenings. The sun sets before 5 p.m. all month, and temperatures drop quickly afterward, especially away from the coast. Plan on T-shirt or light-sweater afternoons and jacket evenings.

Coast vs. inland vs. mountains

San Diego County’s weather changes sharply as you move inland and uphill. NOAA’s normals for three stations show the spread for December:

• Coast, San Diego airport: high 66.0°F, low 49.8°F, 1.67 inches of rain.
• Inland valley, El Cajon: high 68.5°F, low 41.7°F, 1.83 inches of rain.
• Mountains, Julian (Julian CDF station): high 52.2°F, low 38.1°F, 3.47 inches of rain, and about 0.2 inch of snow in an average December.

What the numbers mean for you

El Cajon’s normal December high is actually a couple of degrees warmer than the coast, but its normal low is about eight degrees colder. That wide swing is typical of East County valleys: a sunny afternoon can feel like spring, then the temperature drops into the low 40s overnight. If you are heading to an evening event in El Cajon, Santee or Lakeside, dress for the low, not the high.

Julian and the Cuyamaca Mountains are a different season altogether, with highs in the low 50s and nights near freezing. Snow is light in an average December at the Julian station (about 0.2 inch), while the nearby Cuyamaca station, higher in the mountains, averages about 1.3 inches, so check road conditions and pack a real coat if you are driving up for apple pie and holiday shopping.

Does it rain in San Diego in December?

Sometimes, but not often. At the airport, NOAA’s normals show about 3.1 days in December with at least a tenth of an inch of rain, and about 5.8 days with any measurable rain. El Cajon averages about 3.8 days with a tenth of an inch or more, and Julian about 4.9.

In other words, most December days are dry. A wet forecast usually means one or two rainy days rather than a gray week, so the smart move is to keep plans flexible: put outdoor plans on the dry days and save a museum or theater for the wet one. Many outdoor holiday events run rain or shine, so check each event’s weather policy before you go.

Ocean temperature in December

The Pacific is cool in December. Hourly readings from NOAA’s La Jolla tide station averaged about 62°F in December 2023, 57°F in December 2024 and 63°F in December 2025; the San Diego Bay station averaged between about 60°F and 63°F over the same three Decembers. Year-to-year swings of several degrees are normal.

That is wetsuit weather for most surfers and swimmers. Beach walks, tide-pool visits and sunset watching are comfortable, but plan a quick dip only if you are used to cold water.

Sunrise, sunset and daylight

December has the shortest days of the year. According to the U.S. Naval Observatory, in San Diego:

• December 1: sunrise 6:33 a.m., sunset 4:42 p.m.
• December 21 (winter solstice): sunrise 6:47 a.m., sunset 4:47 p.m., about 10 hours of daylight.
• December 31: sunrise 6:51 a.m., sunset 4:53 p.m.
• Civil twilight ends about 27 minutes after sunset, so it is fully dark by around 5:10 to 5:20 p.m.

Is December a good time to visit San Diego?

For most travelers, yes. December offers mild days, few rainy days, holiday events across the county, and the start of gray whale season along the coast; the National Park Service says whale watching at Cabrillo National Monument runs from late December to mid-March.

What it does not offer is beach weather in the summer sense. The water is cold, the days are short, and nights can be chilly inland. If your trip is about swimming and long sunny evenings, visit later in the year. If it is about holiday events, outdoor walks, hiking without summer heat, and dinners after dark, December works well.

What to pack for San Diego in December

Pack in layers, and pack for the coldest place you plan to be after dark.

• A warm jacket or insulated layer for evenings, plus a light sweater or fleece for daytime.
• A compact rain shell or umbrella for the odd stormy day.
• Closed walking shoes; lawns and trails can be damp in the morning or after rain.
• A beanie and light gloves if you will be out in East County after dark or driving to Julian.
• Sunglasses and sunscreen; bright December days still call for them.
• A small flashlight for dark parking lots after evening events.

How December weather affects evening events

Light shows, boat parades and evening festivals all happen after the 4:40 to 4:55 p.m. sunset, which means you will spend most of an evening event in the coolest part of the day. After dark, temperatures slide toward the normal lows: about 50°F at the coast and the low 40s in inland valleys. Standing still by the water at a boat parade feels colder than walking a light trail, so bring a blanket for seated events.

The Yuletide Medieval Festival at El Monte County Park in Lakeside is one example: it runs rain or shine on the park’s grass, and its Saturday hours on December 5 and 12 extend to 8 p.m., well after dark in an inland valley. Plan for afternoon sun and an evening chill in one visit.

Check the forecast before you go

Normals describe an average December, not this one. A week before your trip, check the National Weather Service San Diego forecast for your exact area, since coast, valleys and mountains can differ sharply, and look again the day before any outdoor event. If a storm is coming, confirm event weather policies and mountain road conditions before you set out.

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