Weather in Costa Rica in September

September is part of Costa Rica’s rainy season—often called the “green season”—and it definitely lives up to the name. Expect regular rain, especially in the afternoons, but that same rain is what makes the country look so alive. Here's our guide to the weather in Costa Rica in September.

Costa Rica in September at a glance

• Temperatures are usually around 75°F (24°C) along the coasts and in the Central Valley.
• September falls in the rainy season, so you can expect afternoon showers, especially on the Pacific coast.
• With fewer tourists around, it’s a great time if you prefer a quieter experience.
• Accommodation and tour prices tend to be lower

What is the weather like in Costa Rica in September?

September in Costa Rica is right in the middle of the rainy season (or "green season"), especially on the Pacific side, where afternoon rain showers are pretty common. You’ll generally get sunny mornings that turn cloudy by midday, followed by afternoon or evening downpours. These showers aren’t light drizzles, but more like intense tropical rains that clear up fairly quickly.

Tourism wise, it’s low season, but there’s a reason fewer people visit during this time. September and October bring the heaviest rainfall of the year, with rainfall ranging from 12-20 inches (300-500mm) on the Pacific coast and in the Central Valley. It’s the wettest month in many regions. The Caribbean coast tends to be a bit drier, making it a good place to consider if the rain gets too persistent elsewhere.

If you’re hoping for lots of sunny beach time or don’t want the rain to mess with your plans, September might not be ideal. But if you’re planning a trip focused on wildlife, lush landscapes, and fewer tourists, it's a great time to visit.

Average daily temperatures

Despite the rain, Costa Rica stays warm in September. Daytime temperatures usually range from 80-88°F (27-31°C), and at night, temperatures cool down to 65-75°F (18-24°C). Since Costa Rica’s close to the equator, days are still pretty consistent, with about 12 hours of daylight—sunrise is around 5:30 AM, and sunset is close to 5:45 PM. For more tips, see our guide to how to plan a trip to Costa Rica.

Pacific Coast

The Pacific coast really feels the rainy season in September. Places like Manuel Antonio, Jaco, and Tamarindo can get afternoon thunderstorms, though mornings usually give you a break for outdoor activities. Temperatures remain warm at 80-88°F (27-31°C). The heavy rain means waterfalls are flowing strong, and the coastal forests are beautifully green. If you're planning on surfing, the waves are pretty consistent, though occasional storms can make the conditions a bit tricky.

Central Valley & Highlands

In the Central Valley, including San José and surrounding areas, expect moderate rainfall in the afternoons. Temperatures stay pleasant, ranging from 65-80°F (18-27°C). Areas like Monteverde and San Gerardo de Dota can get pretty misty, which gives the cloud forests a magical feel. September is a good time for wildlife watching—rainy weather brings out amphibians and reptiles. The misty conditions also help orchids and bromeliads thrive in the highlands.

Caribbean Coast

The Caribbean coast gets some relief from the rain in September. While it still sees rainfall, places like Puerto Viejo and Tortuguero often have a short dry spell in late September. Temperatures here are usually between 75-85°F (24-29°C), and it’s generally the best chance for beach days if you’re in Costa Rica this month. Plus, it’s prime turtle nesting season in Tortuguero.
 

Is September a good time to visit Costa Rica?

September can be a bit of a mixed bag when it comes to visiting Costa Rica. It’s smack in the middle of the rainy season, so heavy rainfall is pretty much guaranteed across most of the country. Outdoor activities can be tough to plan since afternoon downpours are common, and some of the more remote roads might get hard to navigate. If you're hoping to swim at Pacific beaches, the rough seas and runoff can make it less than ideal. That said, the Caribbean coast does get a brief dry spell towards the end of the month, which might give you a better shot at beach days.

There are some perks to September, though. If you're planning a trip to see Costa Rica wildlife, it’s prime time for spotting amphibians and reptiles, as the rains trigger breeding season. Mammals are also easier to spot with their young. The landscape is at its greenest, with waterfalls flowing at their peak. 

What about the crowd & cost?

September is definitely off-season, meaning fewer crowds. Popular spots will feel a lot more peaceful, and some major attractions might have only a handful of visitors compared to the usual rush during high season. This quieter vibe translates to an intimate experience with nature, and you won’t have to worry about making restaurant reservations or reservation accommodations well in advance. The rainy season also means you’ll save quite a bit. 

If you're looking for similar weather but with a better chance of dry days, late November is a good option. It’s the transition from wet to dry season, so you’ll still get some rain but with more chances of sun. See more in our guide to the best time to visit Costa Rica. 

Where to go in Costa Rica in September

September is typically the rainiest month in Costa Rica, especially in the west and central regions. However, the Caribbean side often experiences some of its best weather during this time.

Tenorio Volcano National Park and Río Celeste

Río Celeste looks especially striking in September. The rain actually helps deepen the river’s color—something to do with how the minerals react when the water's moving faster. The trail through the park is around 4 miles and winds through rainforest with a few highlights along the way: hot springs, a big waterfall, and a couple of good lookout points. It’s not a apartment trail—expect mud and a bit of a climb—but it’s manageable. With fewer people visiting this time of year, you’ve got space to move at your own pace, and if you’re lucky, you might see wildlife like monkeys, tapirs, or even an ocelot. This is why it makes it on our favorite Costa Rica rainforest tour.

Guayabo National Monument Archaeological Site

This is Costa Rica’s most important archaeological site, and September’s a nice time to visit if you prefer fewer crowds. The site itself is set in the cloud forest and includes stone walkways, ceremonial areas, petroglyphs, and aqueducts that still work—especially impressive once you see how much water’s moving through them during the rainy season. 

Osa Peninsula

The Osa Peninsula is one of the more remote parts of the country, and in September, it really feels that way. This is when wildlife tends to be most active—there’s more fruit around, so animals like monkeys, sloths, and scarlet macaws are easier to spot. Corcovado National Park has a real wild edge to it during this time. Trails can get muddy, but the waterfalls and rivers are flowing strong, and you’ll hear and see a lot more movement in the trees. On the coast, it’s peak sea turtle nesting season. Some beaches have guided night walks where you can see hatchlings heading to the water.
 

What to do in Costa Rica in September

September’s the rainy season, which might sound like a downside — but it actually changes the whole feel of the country, in a good way. Mornings are usually dry, so you can get out and explore, and by afternoon, the rain rolls in. 
It’s also when Costa Rica celebrates Independence Day, on September 15. If you're around then, expect parades, traditional music and dancing, and plenty of food. It’s not hard to stumble into a celebration — most towns get involved, and it’s a nice way to experience the local side of things.

Whale and Dolphin Festival in Uvita

This is prime whale-watching season on the Pacific coast. Uvita hosts a festival during September, and it’s built around the migration of humpback whales that pass through Marino Ballena National Park. The park’s known for a sandbar shaped like a whale’s tail — you’ll see it if you’re flying in or looking at drone shots — and boat tours head out daily.

You’ve got a good shot at seeing whales and dolphins this time of year, especially moms with calves. The festival also brings music, local food stands, handmade goods, and conservation talks. Even if you don’t go out on the water, it’s a fun time to be in town. This is a great thing to do in Costa Rica with kids.

Go canyoning and waterfall rappelling

This is the season when waterfalls are at their strongest, which makes it a great time to go canyoning. Around La Fortuna and Arenal, there are trips that combine rappelling down waterfalls, hiking through narrow jungle canyons, and ziplining over rivers. Some of the falls are seriously tall — around 150 feet — but everything’s guided, and they’ll walk you through the process.
It’s sweaty, muddy, and a full-body workout, but it’s a blast if you like being out in nature. And afterwards, you can head straight to one of the nearby hot springs to clean off and chill out.

Butterfly Yards at La Paz Waterfall Yards

If you’re not in the mood for something active, La Paz is a solid low-key day trip. The waterfalls there are pretty intense during the rainy season, and the butterfly observatory is at its busiest. There are thousands of butterflies inside, and you’ll usually see some emerging from chrysalides or flying around the paths.
The park’s easy to navigate, with paved walkways and lookouts, and there are other spots to check out too — like hummingbird yards, frog enclosures, and areas for rescued animals like jaguars and pumas. It’s a good all-in-one stop if you want nature without needing to gear up for a hike.
 

Planning your trip to Costa Rica in September

Here are some Costa Rica travel tips for your next trip:

What to pack

September means heavy rain, so full rain protection is essential: waterproof jacket, pants, and a solid cover for backpacks. A poncho can add extra coverage. It’s smart to bring two pairs of closed shoes and several pairs of quick-dry socks and underwear—once something gets wet, it may stay that way for a while. Lightweight, breathable layers still work best since lowland temperatures remain warm. Dry bags or zipper-top plastic bags are helpful for keeping electronics and dry clothes protected inside a backpack. A flashlight or headlamp is a good backup in case of power outages.

Planning your itinerary

Heading to Costa Rica in September? A great way to get started is by looking at sample itineraries for ideas. Here’s some inspiration for your trip:

• Costa Rica itinerary 5 days: Visit San José for cultural experiences, then head to La Fortuna to check out the rainforest and waterfalls. Explore Arenal Volcano’s hiking paths and soak in hot springs, then finish your trip in Monteverde’s cloud forests and hanging bridges. Don’t miss the coffee farm tour on your return to San José.
• Costa Rica itinerary 7 days: Start in San José, spend time in Manuel Antonio’s beaches and rainforests, then explore Monteverde’s Cloud Forest with its hanging bridges and zipper-lining. End your trip in La Fortuna with Arenal Volcano’s trails, waterfalls, and hot springs.
• Costa Rica itinerary 10 days: Begin in San José, then visit Tortuguero’s wildlife canals. Next, head to La Fortuna for rainforest hikes and Arenal Volcano. Spend some time in Manuel Antonio National Park before ending with a relaxing stop at Jaco Beach for surfing and sunsets.
• Costa Rica itinerary 14 days: This comprehensive route starts in San José, with stops at Tortuguero’s canals, Puerto Viejo’s Caribbean vibe, and Cahuita’s coral reefs. Explore La Fortuna and Arenal Volcano, Monteverde’s cloud forests, and finish at Manuel Antonio’s beaches and wildlife.

When to book

September is a quiet month for tourism, and you’ll see the lowest prices of the year. Most mornings are clear, with rain usually rolling in during the afternoon. Costa Rica’s Independence Day (September 15) brings a quick bump in domestic travel, especially in the Central Valley, but otherwise things stay calm.

The Caribbean coast is at its driest now, so it’s a good time to head that way if you want sun without the high prices. You can usually book places with just a couple of weeks’ notice—and sometimes even get a room upgrade or discount.

Emergency weather information

September is usually the rainiest month and brings the biggest risks—especially for flooding. The Central and South Pacific regions get hit hardest, and major storms can affect the whole country. Evacuations sometimes happen near rivers or coastlines, so it’s really important to pay attention to official updates and leave early if asked. Landslides are also a big issue, especially on the Costanera highway and through Cerro de la Muerte. If you’re driving, keep emergency food, water, and a flashlight in the car just in case you get stuck. Even though the Caribbean coast is usually drier, it’s still not immune to big downpours. 

 For more travel inspiration, see our guide to creating your own Costa Rica itinerary, with tips from local travel experts, or find extra ideas in our Costa Rica travel guide and tailored Costa Rica trips.