If you’re looking for warm places to visit in the US in December, your main choices will lie between humid, beach-friendly weather in the Caribbean and southern Florida or dry desert sun in the Southwest.
That difference affects what you pack and how you spend the day. The humid destinations suit a trip built around swimming, beaches, and warm evenings outside, while the desert gives you sunny days without the sticky air.
Because these are domestic trips for US citizens, you can focus on the weather, travel time, and fare without adding passport logistics. We’ll look at the warmest options, what December actually feels like in each one, and when to fly to avoid the highest holiday prices.
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Which US regions stay warm in December
Among the warm places to visit in December in the USA, three areas stand out: Puerto Rico and southern Florida, the desert Southwest, and Hawaii. Puerto Rico and southern Florida stay warm because of their tropical and subtropical locations; Palm Springs has a dry desert climate, and Hawaii keeps tropical temperatures through winter because of its Pacific island location.
The important part is that “warm” does not feel the same in all three.
Puerto Rico and southern Florida
San Juan, Key West, and Miami are the closest match to summer. Daytime temperatures stay relatively high, the air is humid, and nights are still warm enough for dinner outside without reaching for a heavy layer.
This is the group to look at if your December trip includes swimming, beach time, or long days outdoors in light clothing. You will notice the humidity throughout the day and into the evening.
Palm Springs and the desert Southwest
Palm Springs has a very different kind of December warmth. Days are dry, sunny, and warm, with little humidity, while temperatures fall sharply after sunset and nights feel much cooler.
That means you can hike or sit outside comfortably during the day without the sticky air you get in southern Florida, then need a jacket once the sun goes down.
Hawaii
Hawaii stays warm enough for beach days through December, too. The difference is the distance. From much of the mainland, you will spend more time getting there than you would flying to Florida or Southern California.
For a week-long trip, that extra flight time is easier to absorb. For a three- or four-day break, it takes a noticeably larger bite out of the time you have at the destination.
All three are domestic trips for US citizens. Puerto Rico, also being a US territory, doesn’t require a passport for travel, and you use US dollars once you arrive. That keeps Puerto Rico in the same planning category as other warm places to visit in the US in December, even though it is in the Caribbean.
Puerto Rico and the Florida Keys: humid Caribbean warmth without a passport
San Juan and Key West are the two strongest choices in this group if you want December to still feel like beach season. San Juan averages about 84°F (31°C) during the day and 79°F (26°C) overall, while Key West has a normal December high of 77.7°F (25°C). That puts both among the best warm places to visit in the US in December if swimming and time outdoors are high on the list.
The choice between them is mostly about the kind of trip you want. San Juan gives you the warmer weather and a Caribbean city break, while Key West keeps you in Florida and has a smaller island feel.
San Juan, Puerto Rico
San Juan is the warmer choice. December nights average about 73°F (23°C), so you can still eat outside or walk through Old San Juan in a T-shirt or light layer after sunset.
During the day, El Morro and San Cristóbal give you an easy way to spend several hours outside while seeing two of the city’s major historic sites. These forts protected San Juan from attacks by sea and land, and both fit naturally into the same Old San Juan visit.
For US citizens, reaching Puerto Rico is much like taking any other domestic flight. You arrive at Luis Muñoz Marín International Airport (SJU) and go through the same basic arrival process as you would on a mainland domestic trip.
You might also like to read: How to Score Cheap Flights to Puerto Rico.
Key West, Florida
Key West is cooler than San Juan, but December still leaves plenty of room for the beach and water. The average high is 77.7°F (25°C), the average low is 68.3°F (20°C), and coastal water temperatures are about 75°F (24°C).
That keeps snorkeling realistic through December. You can spend part of the day along Duval Street, then head offshore to one of the shallow reef areas within Florida Keys National Marine Sanctuary.
Key West fits a slow trip. Once you arrive, the main sights, restaurants, and waterfront areas are concentrated in a small part of the island, so you can spend less of the day moving between places.
Miami, Florida
Miami is the easier alternative if you want southern Florida temperatures but do not specifically need the Keys. December highs stay near the upper 70s (25°C), and Miami International Airport (MIA) has far more domestic flight options than Key West, which gives you more arrival and departure times to compare.
That advantage becomes especially useful on a short trip. You can land in Miami and start the vacation there almost immediately instead of adding the drive south through the Keys. You are still getting warm days and humid air throughout December.
Palm Springs and the desert Southwest: warm and dry instead of humid
Palm Springs is the desert alternative to Puerto Rico and southern Florida. December afternoons average about 69°F (21°C), but the dry air changes how that warmth feels. Nights drop to about 47°F (8°C), so a T-shirt can be enough during the day while you’ll want a jacket after sunset.
Rain rarely interrupts plans in December. Palm Springs gets about 0.7 inches (1.8 cm) of precipitation for the month, spread across only about three days, so most days are dry.
That combination of dry air and daytime warmth suits an active trip. Indian Canyons has more than 60 miles (97 km) of hiking and walking trails through palm oases and desert terrain, while the Palm Springs Aerial Tramway takes you from the desert floor to the Mountain Station at 8,516 feet (2,596 m) in about 10 minutes. The temperature at the top is typically 30°F–40°F (17°C–22°C) lower, so bring a warm layer. You’ll want it as soon as you step off the tram.
Tip: If humid weather makes you overheat quickly, compare humidity with temperature when choosing between Palm Springs and Miami. Palm Springs is cooler on paper, but its dry air can make a full day outside feel much less muggy than southern Florida.
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How to find a cheap flight to warm parts of the USA in December
The simplest way to pay less for a December trip is to avoid the Christmas and New Year travel rush. Holiday demand rises sharply from December 20 onward, while San Juan, Key West, Miami, and Palm Springs are already warm earlier in the month.
That gives you an advantage when looking for cheap warm places to visit in the US in December. You do not need to wait until Christmas week for beach weather in Puerto Rico or southern Florida or sunny afternoons in Palm Springs. Moving the trip into the first half of December can give you the same type of weather without competing with peak holiday demand.
For Christmas 2026, waiting until November is risky. We recommend buying domestic Christmas flights by Halloween, but this year, booking even earlier is the safest strategy. Airfare tracking for the 2026 holiday season shows that Christmas 2026 fares are already 12% to 18% higher than for the 2025 holiday period.
When you buy your ticket absolutely matters, but the day you fly can also change the price. Monday-through-Wednesday departures are typically cheaper than weekend flights; flying midweek during the holidays can save $100 or more per ticket. If you need to travel during Christmas or New Year’s, compare fares for the holiday itself with the days immediately before it, since flying on Christmas Day or New Year’s Day is cheaper than traveling just before the holiday.
If your holiday dates aren’t fixed yet, Ovago’s Flexible Ticket lets you change the date or time of your flight without paying the change penalties.
For a lower December fare:
- Travel before mid-December to avoid the main Christmas and New Year rush.
- Fly Monday through Wednesday when your schedule allows, since midweek fares are typically lower than weekend fares.
- Hurry to buy Christmas flights as soon as you find a fare that fits your budget. October is the right time to do it.
San Juan is the simplest place to start
For a first warm-December domestic trip, San Juan gives you the clearest mix of warm weather and simple planning. It has the highest December temperatures of the destinations covered here, and US citizens can travel without a passport and use US dollars once they arrive. If your goal is to get somewhere genuinely warm without adding the usual steps of an international Caribbean trip, San Juan is the best place to do so.
