Carry-On Only for San Diego: SAN Airlines, Climate & Packing Tips

San Diego has a strong argument for the best year-round climate of any major city in the United States. Temperatures stay between 18 and 28 degrees Celsius for most of the year, rain is rare, and sunshine is the default. For carry-on travelers, this climate is a gift — light summer clothing covers almost every month of the year, with only minimal additions needed for the occasional cool evening or cloudy morning.

Airlines at San Diego International Airport

San Diego International Airport (SAN) serves a wide range of carriers and sits just 5 km from downtown — one of the most convenient major airport locations in the US. There is no rail link, but the short distance makes taxi and ride-share trips quick and affordable.

Southwest Airlines is a major presence at SAN and offers its standard passenger-friendly policy: one free carry-on plus one personal item for every passenger regardless of fare type. Southwest is one of the best choices for carry-on travelers at any airport it serves.

Alaska Airlines serves SAN with a carry-on included on most fare types. American, Delta, and United all fly SAN; Basic Economy fares on each restrict overhead bin access, so check your fare class before booking.

Spirit and Frontier both serve San Diego and charge separately for carry-on bags. Volaris serves SAN with routes to Mexico — useful if you are combining a San Diego trip with time in Tijuana or other Mexican cities.

Packing for San Diego: The Light List

San Diego's near-perfect Mediterranean climate means your packing list is shorter than almost any other major US city destination.

Core packing for most of the year: light t-shirts and shirts, shorts or light trousers, comfortable walking shoes, swimwear, and sunscreen. That is genuinely most of what you need for spring, summer, and autumn visits.

Sunscreen is the most important liquid in your toiletry bag for San Diego. The sun is intense year-round, the beaches require protection, and the TSA liquids rule (containers of 100 ml or under, all in one quart-sized bag) limits how much you can carry. Buy a larger bottle in San Diego if you are staying more than a few days.

One light layer — a thin long-sleeved shirt, light cardigan, or packable windbreaker — is useful for evenings, air-conditioned restaurants, and the marine layer mornings of May and June (June Gloom). San Diego evenings cool noticeably even in summer, particularly near the coast.

Swimwear is essential. San Diego has some of the best urban beaches in the United States: Mission Beach and Pacific Beach for social energy, La Jolla Cove for dramatic scenery and sea lion watching, and La Jolla Shores for calm water and snorkeling. Pack at least one swimsuit.

Winter in San Diego

San Diego winters (December through February) are mild by any standard: daytime temperatures around 16 to 20 degrees Celsius, occasional rain, and nights that can drop to 10 degrees. For most visitors from colder climates, this feels like spring.

A light jacket or mid-weight layer handles San Diego winters comfortably. You do not need a heavy coat, thermal base layers, or winter boots. One extra layer on top of your standard light wardrobe is sufficient.

Balboa Park and the San Diego Zoo

Balboa Park is the cultural heart of San Diego — a 490-hectare urban park containing 17 museums, the world-class San Diego Zoo, beautiful gardens, and performance spaces. The park is free to enter and walk, though individual museums and the Zoo charge admission.

For Balboa Park visits, comfortable walking shoes are more important than anything else. The park is large and hilly, and doing it justice means covering real ground. The Museum of Man, the San Diego Museum of Art, and the Natural History Museum are all excellent. The Zoo requires a full day to see properly.

La Jolla, the Gaslamp, and Coronado

La Jolla, about 20 minutes north of downtown, is one of San Diego's most beautiful neighborhoods: dramatic cliffs, the La Jolla Cove with harbor seals, and the La Jolla Shores beach. The village has excellent restaurants and galleries. Getting there requires a car or ride-share.

The Gaslamp Quarter — downtown San Diego's historic nightlife and restaurant district — is walkable from most downtown hotels. Little Italy, immediately north of the Gaslamp, is one of San Diego's best dining neighborhoods. Both areas are flat and compact.

Coronado Island is reachable by ferry from downtown in about 15 minutes (a pleasant trip in itself) or by car via the Coronado Bridge. The Hotel del Coronado is a Victorian-era landmark worth visiting even if you are not staying there. Coronado's beach is consistently ranked among the best in the United States.

Tijuana Day Trip

San Diego sits 30 minutes from Tijuana, Mexico, and the combination makes for one of the most distinctive day trips in North America. The San Diego Trolley Blue Line runs to the San Ysidro border crossing; cross on foot into Tijuana for food, shopping, and a genuinely different urban experience. Bring your passport. The return queue at the US border can be long — allow extra time heading back.

The Carry-On Only Verdict

San Diego is among the easiest US cities for carry-on only travel. The warm, stable climate reduces packing complexity to almost nothing — light clothes, swimwear, sunscreen, and one evening layer covers nearly every itinerary. One carry-on bag is all you need for a San Diego trip of almost any length.