Tamarindo in September (2026): Wettest Month, Lowest Prices & the Arribada

⭐ Best September window: whenever an arribada is running. Unlike every other month on this calendar, the thing worth timing is not weather or crowds, both of which are flat all month. Arribadas cluster around the last quarter moon but are not precisely predictable, so if the turtles are the reason you are coming, build in flexibility rather than fixed dates.

💰 Average September hotel prices (Tamarindo town, mid-range):
Most of the month: ~$100–150/night
Rough mid-range estimates; rates vary widely by property, location and booking lead time.

September is the month Tamarindo stops pretending. Around 359mm of rain across roughly 17 days makes it the wettest of the year, a clear step up from August, and it is the point where the green season case gets genuinely harder to make. The town is quiet in a way it is not at any other point in the calendar, and rates fall to their annual floor.

What stops this being a write-off month is two things. The water offshore is still close to its August peak, so the snorkeling and diving that make August the best month underwater have barely declined. And the Ostional arribada starts, which is one of the genuinely extraordinary wildlife events on the continent and something no dry-season visitor will ever see.

Our take: September is a specialist month and we would not pretend otherwise. We'd book this if you are chasing the arribada or diving on a budget, and we'd look elsewhere for a general beach holiday. Most people don't realize that the cheapest month of the year also carries the single most spectacular natural event in the Guanacaste calendar, which is a strange thing for the market to have priced this way.

Temperature and Humidity

Highs hold around 31°C (88°F) with lows near 23°C (74°F), essentially unchanged from August. Cloud cover keeps the heat well below the April peak, and the practical experience is warm and heavily humid rather than hot. Nothing about the temperature is difficult in September; it is entirely a rain question.

Rain Pattern

Around 359mm across roughly 17 rain days, the wettest of the year. Note that September carries fewer rain days than August but considerably more water, which tells you something useful: the rain is heavier when it comes rather than more frequent. September showers are more likely to be substantial downpours than the brief afternoon bursts of May and June.

The morning pattern does still hold, and this is the thing that keeps September workable. Rain concentrates in the afternoon and evening, so a morning-first itinerary is still viable. What changes from earlier months is the planning posture: in May you scheduled mornings to protect against rain, and in September you should assume the afternoon is gone and treat a dry one as a bonus.

Sea Conditions

Water stays warm at around 28°C (82°F) and offshore visibility remains close to its August peak, which is the single most underrated fact about this month. The conditions that make August the best month in the water have not meaningfully declined by September, and they are available at the lowest prices of the year.

The near-shore caveat is stronger than ever. With the year's heaviest rainfall, river runoff clouds the water close to land more than in any other month, so beach snorkeling is poor. The offshore sites at the Catalinas are where the clarity is, and getting out to them matters more in September than in August.

This is the emptiest and cheapest month of the Tamarindo year, with no meaningful variation inside it.

The annual floor

Mid-range rooms fall to roughly $100 to $150 a night, the lowest of the calendar and less than half what the same room costs in March. Tours run with same-day availability, restaurants take walk-ins without exception, and the beach is close to deserted outside the occasional clear evening.

Unlike June, which had a value window that closed at month end, September is flat. There is no better or worse fortnight on price or crowds, which is why the arribada rather than the calendar should drive your dates.

What closes

Some hotels and restaurants in Guanacaste close during the deepest part of green season, and this is worth planning around rather than discovering. The effect is more pronounced in October than September, but by late September you should expect a thinner selection than the brochure suggests. We'd confirm this before booking: check that the specific places you want to eat at or stay in are actually open on your dates rather than assuming the town operates normally.

The honest value calculation

Against August, September is cheaper and quieter with marginally worse weather and marginally worse water, plus the arribada. Against the second half of June, September is cheaper again but significantly wetter.

We'd book this if you are diving or snorkeling on a budget, since the water is near its annual best at the year's lowest rates. We wouldn't choose it for a first trip to Costa Rica, for a short holiday, or for families with young children, because the rain is heavy enough to cost you real days and there is less open to fall back on.

Guanacaste has two completely separate turtle stories, and they happen at opposite ends of the year. The one most Tamarindo visitors hear about is the leatherback nesting at Playa Grande, which runs October to April. The one that happens in September is bigger by orders of magnitude.

What an arribada is

At Ostional Wildlife Refuge, olive ridley turtles come ashore not individually but en masse, in an event called an arribada. Thousands of turtles nest over a period of roughly three to four days. The season runs from September through November, with September and October the peak, and Ostional hosts among the largest arribadas anywhere in the world.

Getting there from Tamarindo

Ostional sits roughly two to two and a half hours south of Tamarindo on the Nicoya peninsula, so this is a committed day rather than a local excursion, and the roads in that direction are less forgiving in the wettest month of the year. Access is regulated and guided: this is a protected refuge, not a beach you wander onto.

The honest problem with planning it

Arribadas are not scheduled. They cluster around the last quarter moon, and local guides forecast them with reasonable but not complete accuracy. A fixed one-week trip booked months ahead may or may not coincide with one.

What we'd suggest is treating it the way you would any wildlife event rather than an attraction with opening hours. If the arribada is the reason for the trip, build flexibility into your dates, ask locally once you arrive rather than relying on a schedule found in advance, and have a plan that does not collapse if it does not happen. We'd shortlist September for this above any other reason to come, while being clear that it is a chance rather than a booking.

Our Tamarindo turtle tour guide covers the closer Playa Grande leatherback tours, which are a different species, a different season and a completely different scale of event.

Additions worth making to a September itinerary that have no dedicated guide:

• The Ostional arribada. Two to two and a half hours south, guided access only, and the most spectacular wildlife event in the region. Ask locally about timing once you arrive rather than planning it from home.
• Scuba diving at the Catalinas. Visibility is barely off the August peak and prices are at their annual floor. For divers this is the best value fortnight of the year.
• Waterfalls at maximum flow. Llanos de Cortes and the regional falls are carrying the heaviest rainfall of the year, which is the exact opposite of their March condition.
• Three indoor options, not two. Cooking classes, coffee and chocolate tastings, a spa afternoon. In the wettest month you will use all of them.
• Empty sunset beaches. On a clear evening in September you can have Playa Tamarindo or Playa Grande almost to yourself, which is impossible in any dry-season month.
• Check what is open before you go. Some Guanacaste hotels and restaurants close through the deepest green season. Confirm your specific choices rather than assuming a normal selection.

• Assume the afternoon is gone: This is the planning shift from earlier green-season months. In May you scheduled mornings to hedge; in September you should treat a dry afternoon as a bonus rather than a plan.
• Book offshore, not beach, for snorkeling: The year's heaviest rain means near-shore water is at its cloudiest. The Catalinas hold clarity; wading in off the sand does not.
• Confirm what is actually open: Some Guanacaste hotels and restaurants close through the deepest green season, more so from October. Check your specific places rather than assuming the town runs normally.
• Treat the arribada as a chance, not a booking: Ostional arribadas cluster around the last quarter moon but are not precisely predictable. Build in flexible dates, ask locally on arrival, and do not let the trip depend on it.
• Allow extra time for the drive south: Ostional is two to two and a half hours away, and the roads in that direction are less forgiving in the wettest month of the year.
• Take advantage of the smallest groups of the year: Surf lessons, snorkel boats and wildlife tours all run emptier in September. If instructor or guide attention matters to you, this is when you get the most of it.
• Keep three indoor fallbacks ready: Two was enough for August. At 359mm across 17 days you will work through more of them than you expect.
• Do not book Rio Celeste: Peak upstream rain over Tenorio makes brown water close to a certainty. This is the one month we would rule it out entirely rather than caveat it.
• Visiting at a different time of year? Our Tamarindo in October guide covers the next month, when leatherback nesting opens at Playa Grande while the arribada is still running, and the rains start easing at month end. Our Tamarindo in August guide covers the clearest water of the year at better odds on the weather.