Even if you’re a big fan of snowy mornings and cozy nights, winter can sometimes bring on the blues.

The shorter, colder days cause millions of Americans to feel fatigue, depression and other symptoms that may indicate seasonal affective disorder, according to the National Institute of Mental Health.

Although serious cases of SAD can require medical or mental health treatments, experts say getting a splash of warm sun at this time of year can help with milder cases of the winter blahs.

“If you fly south, you’re flying to an environment where the sun comes up earlier and goes down later, so you are getting a very powerful, immediate change in the circadian stimulus,” said Dr. Paul Desan, an associate professor of psychiatry at the Yale School of Medicine.

“A tropical vacation may really help you,” he added. “It’s not your imagination.”

You don’t have to travel too far or spend all that much to reap the benefits of a sunny midwinter boost. Here are six easy warm-weather getaways.

San Juan, Puerto Rico

San Juan, the capital of Puerto Rico, is the gateway to a string of beautiful beaches along the island’s northern coast. In Condado, an oceanfront community just 15 minutes east of the cobblestone streets of Old San Juan, you’ll find plenty of sand, along with shopping, nightlife and hotels like the luxurious, century-old Condado Vanderbilt.

Drive west of the city to discover a range of small towns and sandy shores, including La Poza del Obispo, or the Bishop’s Pool, which features a semicircular inlet protected from the waves.

Back in San Juan, explore the museums, historical sites, shops, bars and restaurants in the narrow streets of Old San Juan, which comes to a point overlooking the spot where San Juan Bay meets the Atlantic Ocean at the Castillo San Felipe del Morro, a Spanish fortress built in the 1500s. On a sprawling green lawn nearby, families picnic, children fly kites and vendors sell refreshments like piragua, shaved ice with fruity syrup, in case you need to cool off from the 85-degree average high temperature during the winter months.

Las Vegas

Las Vegas is known as the entertainment capital of the world, but it’s also dry, sunny and mild in the winter — average temperatures in January are in the high 50s — and offers a surprising array of outdoor activities like hiking, rock climbing and riding ATVs.

The famous hotels and casinos along the Strip feature plenty of entertainment beyond gambling: For starters, be mesmerized by the acrobatics of Cirque du Soleil or wowed by the magic of David Copperfield at the MGM Grand.

It’s hard to miss one of the newest attractions nestled into the city’s skyline, the Sphere, an illuminated arena shaped like an orb. If there’s not a concert planned for the time you are visiting, you can still buy tickets for an immersive experience like “Postcard From Earth,” a 2023 film directed by Darren Aronofsky.

If you’d rather get outside, take a day trip to see the engineering marvel Hoover Dam, or join a kayak tour (half-day tours from $149) to see the dam and then explore the Black Canyon along the Colorado River just downstream. If you’re more into hiking, head west into the Mojave Desert to Red Rock Canyon National Conservation Area ($20 per vehicle), which offers both gentle loops and strenuous scrambles among scenic mountains, cliffs and canyons.

Puerto Vallarta, Mexico

Puerto Vallarta, on Mexico’s Pacific Coast, is famous for its popular Zona Romántica, a trendy area filled with LGBTQ+ bars, courtyard cafes and contemporary art galleries. Along one of its main streets, Basilio Badillo, also known as restaurant row, you’ll find shops, shows like racy musical comedy by the Vaude-Villains, the brother band Los Bambinos playing the Beatles, or the “Best of Broadway” musical revue, as well as dozens of dinner spots that are perfect for date night.

The resort town has an average temperature of 80 degrees during the winter, with few rainy days, so you may want to take a swim at one of the beaches hugging Banderas Bay. Then dry out by taking a stroll along the Malecón, a pedestrian walkway that stretches 12 blocks along the coast and is dotted with restaurants, street art, craft vendors and sculptures of lovers, mythological gods and sea creatures.

You’ll find 79 acres of oak, magnolia, agave, cactus and native Mexican species at the Vallarta Botanical Garden (admission, 300 pesos, or about $14.50). Check out sculptures and local crafts on Cuale River Island, a downtown park and cultural center. Or if you’re looking for some adventure, book an excursion to hike to the Cerro de la Cruz lookout for a sunrise over the mountains, zip line through lush rainforest or swim with Pacific bottlenose dolphins at the Marine Mammal Center.

Cartagena, Colombia

Cartagena, on Colombia’s Caribbean coast, will charm you with its vibrant culture, including the walkable Old Town, a walled district built in the 16th century where you’ll find colorful colonial buildings as well as cobblestone streets, churches and plazas.

You may run across traditional festivals and Indigenous crafts on display, and you’re sure to hear music emanating from all corners of the city, like the ubiquitous cumbia, which was born in Colombia; the mapalé, an Afro-Colombian style; champeta, a genre and dance common in Caribbean Colombia; and, of course, salsa.

Beyond the restaurants, bars and boutique hotels, you can explore the Castillo de San Felipe de Barajas (admission, 33,000 pesos, or about $7.50), a hilltop fortress dating back to the 17th century. Learn about the pre-Columbian history and people of the region while admiring ancient artifacts, many of them gold, at the Museo del Oro Zenú (free admission) or dig into colonial-era history at Museo San Pedro Claver (admission, 28,000 pesos, about $6).

Oahu

This Hawaiian island, home to the high-rise hotels of Waikiki, offers families several kid-friendly reasons to get out of the hustle of Honolulu.

About a 30-minute drive west from the airport, Aulani, a Disney resort and spa, features pools, slides, a splash zone and a private saltwater snorkeling lagoon, as well as a beach, excursions, entertainment and, of course, the Disney character experience where guests can meet classic characters like Mickey Mouse and Minnie Mouse, or local favorites like Stitch and Moana.

Not far away, at Coral Crater Adventure Park, thrill-seekers can find zip lining, ATV off-roading and an obstacle course called the Adventure Tower (starting at about $60), where you can climb and swing through 18 different challenges, including a high ropes course and a 50-foot free fall.

El Salvador

If you were dreaming of carving waves instead of turkey this past Thanksgiving, El Salvador may be the place for your midwinter getaway.

La Libertad, an area that is quickly becoming a popular surfing hot spot, is only about 45 minutes from the international airport. Farther down the coast, the beach towns and growing surf meccas of El Zonte and El Tunco offer breaks for surfers of all levels. And you don’t even need to pack your board: You can buy one from local surf shops or rent one from a hotel like Puro Surf, which also offers lessons. Other hotels like Esencia Nativa offer not only surf lessons, dining and accommodation, but also excursions to places like the picturesque towns along the Ruta de las Flores, the beautiful and swimmable Tamanique Waterfalls, or the stunning Santa Ana Volcano and its crater lake, Lago de Coatepeque.