Tamarindo in September: Rainy Season, Arribada Peak and Tours

5 min read · Tamarindo Estuary Tours Mi Rey

Photo: Scott Cresswell from Melbourne, Australia, CC BY 2.0

Tamarindo in September is the town at its most local. Most visitors stay away because of the rain, the beaches are nearly empty and the mangroves are as full and green as they get all year. Out on the estuary, shared tours usually run with small groups, and the main question of the day is not where to go but when the tide and the clouds will line up.

Short answer: Tamarindo in September is wet, green and quiet. Expect rain on most days, sometimes for several days in a row, but also bright mornings that suit estuary tours on a morning tide. It falls within the peak of the Ostional arribadas, groups are small and Independence Day on 15 September is the main holiday. Travel with flexible plans and the month rewards you.

Tamarindo weather in September

September and October are usually the wettest months of the year in Guanacaste. Many September days still follow the familiar pattern: a clear or partly cloudy morning, clouds building after lunch and rain in the afternoon or evening.

The difference with August is frequency and intensity. Downpours are heavier, storms are more common and some weeks bring a temporal, a spell of several overcast days with steady rain.

The Pacific swell also tends to be bigger in these months. Surfers welcome it, but some beaches become less suitable for swimming, so check the conditions and the flags before going in. The estuary, by contrast, is sheltered from the waves. For the whole green season, see our guide to the Tamarindo rainy season.

Costa Rica in September: Independence Day and quiet beaches

September is low season. Hotels and restaurants are quiet, and some local businesses take their own holidays or shorten their hours, so check ahead if a particular place matters to you.

The one big date is 15 September, Independence Day:

14 September, evening: children parade with handmade lanterns, called faroles, and the Freedom Torch, carried by runners across Central America, arrives in Costa Rica.
15 September: schools and marching bands parade in towns across the country.

It is a public holiday and can bring national visitors for a long weekend, but it rarely fills Tamarindo the way the July or December holidays do.

Tamarindo in September: peak arribada season

Ostional arribadas: September falls within the peak, which usually runs from September to November, when the largest arribadas of the year tend to occur. Each one lasts several days and roughly one happens per month, but the turtles decide when it starts.
Nesting near Tamarindo: olive ridley and black turtles nest on nearby beaches, and our night tour visits Playa Minas or Playa Jesús.
Leatherbacks: their season at Playa Grande begins in October, and sightings are now rare.
Baby turtle releases: our sunset release tour is available from November 12.

Before you go, read our guide to the Ostional arribada tour to understand the beach rules and the timing.

What our guides see on the estuary in September

Northern migrants are arriving. At low tide, migratory shorebirds feed on the mudflats near the river mouth, and ospreys become easier to spot over the channels as the months go on.

Crocodiles live in the estuary all year, and on grey days they often float in the channels rather than bask on the banks. In the dry forest, howler monkeys are active among the leaves and frequently call before or after a shower. Every sighting depends on nature; our guide to wildlife tours in Tamarindo explains what lives where.

How rain and tides affect tours in September

Boat and kayak tours leave with the high tide, which changes every day, and we confirm the exact time by WhatsApp after you book. In September, the time of the tide matters more than in any other month.

Morning tides: use them for the estuary whenever your stay has them.
Afternoon tides: go anyway when the sky allows. A warm shower on the boat is part of the green-season experience.
Storms or unsafe water: we wait, offer another date or refund the deposit.
Waterfalls: trips leave early. After heavy rain the water can be higher, stronger and less clear, and the guide decides on the day whether swimming is safe.
Ostional: the road is partly unpaved, so the drive can take longer after a wet week.

Is Tamarindo in September right for you?

Choose September if

Seeing an arribada is high on your list.
You prefer empty beaches, small groups and a relaxed town.
You enjoy green landscapes and do not mind getting a little wet.

Consider another month if

You want long, sunny beach days; look at December to April instead.
Your trip is very short and every day has a fixed plan; heavy rain could force a change.

What to pack for a rainy September

A good rain jacket or poncho, not just a light layer.
Quick-dry clothes, and sandals or water shoes that drain well.
Zip-lock bags for your phone and documents.
Insect repellent: mosquitoes are more active in the wettest months.
Dark clothing and a camera without flash for turtle tours.

Things to do in Tamarindo in September: best tours

Ostional arribada tour: $130 per person, minimum 4 people, children 3 and under free, with transportation from Tamarindo or Langosta, a bilingual guide, water and seasonal fruit. Deposit $20 per person.
Tamarindo estuary tour by shared boat: $40 per person, 2 hours, minimum 2 people. The best rainy-day option, because light rain does not stop it.
Tamarindo turtle tour: $60 per person, minimum 2 people, pickup in Tamarindo at 5:30 pm.
La Leona waterfall tour: $160 per person, minimum 4 people, 7 am to 3:30 pm, with transportation, entrance tickets, drinks and a Costa Rican lunch. Bring water shoes and tennis shoes.

Comparing months? Tamarindo in August has a little less rain, and Tamarindo in October continues the arribada peak with even fewer visitors.

Thinking about September? Tamarindo Estuary Tours Mi Rey will match your tours to the tides and the next arribada. Book online with the deposit and pay the balance on the tour day, or write to us on WhatsApp with your dates and we will suggest the best plan.

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Frequently asked questions

Is it worth visiting Tamarindo in September?

Yes, if you accept rain as part of the trip. September is one of the wettest and quietest months, but many mornings are still bright, crowds are small and it falls within the peak of the Ostional arribadas.

Does it rain all day in Guanacaste in September?

Usually not. Most days have dry hours, often in the morning, but September can bring spells of several cloudy, rainy days in a row. Keeping your plans flexible is the best strategy.

What happens on 15 September in Costa Rica?

Costa Rica celebrates its independence. On the evening of 14 September children carry handmade lanterns in parades, and on the 15th schools and marching bands parade in towns across the country.

Is September the best month for the Ostional arribada tour?

September is within the peak, which usually runs from September to November. Arribadas still follow nature, so write to us on WhatsApp to ask when the next one is expected before you fix your dates.

What happens if rain affects my boat tour in September?

Light rain does not usually stop a boat tour. If the weather or water conditions make it unsafe, we contact you to offer another date or a refund of the deposit.

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