Costa Rica is divided into two seasons rather than four: the rainy season and the dry season. You'll be arriving in the dry season, which lasts from December through April. This happens to coincide with the high tourist season as well. These are the hotter months in Costa Rica, with temperatures averaging in the 80s and peaking in the 90s Fahrenheit—but December is close enough to the end of the rainy season that temperatures may be milder.
Crowds & Costs
There's no getting around the fact that December in Costa Rica is most decidedly the high season. International flights are going to be more expensive, and there might be an increase in domestic fares as well. Also, hotel prices can jump 10, 15, 30 and even 50% higher (in certain locations) than during the low season. The key is to make reservations well in advance and consider visiting some more off-the-beaten-path destinations, which we outline below.
Where to Go
Even though it might seem counterintuitive, you may want to save some of that vacation schedule for the capital city of San José (rather than merely using it as an embarking/departure point to other areas). There's no shortage of Christmas festivities occurring during this month, whether it's the bright lights of the Festival de las Luces or the horse parades of El Tope Nacional. You can read more about visiting Costa Rica during the holidays.
That isn't to say you should spend all your vacation time in the capital. If you want to enjoy Costa Rica's natural beauty while avoiding the tourist hordes, perhaps spend two or three days in Tortuguero National Park, located on the Caribbean coast of the country. Here you can observe sea turtles and take river cruises. Or head down the coast to the surf haven of Puerto Viejo. Even if you're not a wave-rider you can enjoy the small-town atmosphere, Afro-Caribbean culture, and crystalline waters.
What to Do
If you decide to go off the beaten path, consider the Osa Peninsula, located on the southern Pacific coast. This is one of the most remote parts of Costa Rica and is thu less crowded, even during the high season. Moreover, it's the location of Corcovado National Park, one of the most biodiverse areas in the country. A day trip into this park for some waterfall treks and wildlife spotting would be a unique change of pace from your typical holiday merrymaking. Here's more info on Osa.
If you're traveling with family, a good idea is to enjoy some beach time with the kids on the Pacific coast. The town of Nosara is particularly beautiful and the beaches here with their small waves are particularly great for kids. Parents can get some relaxation in with a bit of yoga time and massages.
Events in December
Festival de las Luces. This month-long Christmas celebration in San José kicks off in early December and features live concerts, light shows, parades, and more.
Christmas Eve. Christmas mass is held and local families distribute homemade tamales to friends.
El Tope Nacional. On December 26th this annual celebration features a horse parade through the streets in the city center.
San José Carnival. The capital holds its own one-day carnival celebration on December 27th that features ornate floats, processions of costumed locals, and live music.
Traveling to Costa Rica in December? Check out these great itineraries.
Explore Tortuguero from San José. After spending a day exploring San José's fun holiday offerings, you can get away from the crowds and make your way east to the untouched beaches of Tortuguero. Delve deeper into the park and paddle a canoe around its arterial waterways, keeping an eye out for plenty of other wildlife along the way.
Osa Peninsula Off the Beaten Path. The Osa Peninsula is located in one of the most remote areas of Costa Rica. It's brimming with beaches and virgin rainforest home to an abundance of exotic wildlife. In a mere five days, you'll fully explore this gem of biodiversity through nature hikes, scuba diving, and other adventurous activities.