September is the month the map flips. The Pacific has its wettest month of the year at about 330 mm and much of it effectively closes; the Caribbean has its driest at 160 mm and comes into its own. It is the cheapest month in Costa Rica, and the one where going to the wrong coast is a genuinely expensive mistake.
The rain map, inverted
Compare this chart with the July one. Guanacaste has gone from 140 mm to 330; Puerto Viejo from 400 mm to 160. Nothing else in the Costa Rican year is this stark, and it is the single most valuable thing to understand about the country’s seasons.
Go to the Caribbean
September and October are the Caribbean coast’s window, and almost nobody uses it.
- Puerto Viejo, Cahuita and Manzanillo get their most reliable sunshine of the year.
- Cahuita National Park – walk-in, donation-based at the Kelly Creek entrance, with sloths, howlers and one of the country’s few decent snorkelling reefs.
- The culture is different from the Pacific side – Afro-Caribbean, with its own food (rice and beans in coconut milk, rondón), its own Mekatelyu English creole, and a far slower pace.
- Tortuguero is still in green turtle season to about October.
What closes on the Pacific
Continue planning your Costa Rica trip
This is the practical warning. September and October are when many Pacific-side lodges, tour operators and restaurants close entirely for their annual maintenance break – particularly in Manuel Antonio, the Osa peninsula and the smaller Nicoya beach towns. Some national park trails close too, and Corcovado has had September–October closures in the past.
Check that your specific lodge and the specific park are open before booking a Pacific trip in these two months. It is not a general slowdown; individual businesses simply shut.
The arribadas
One of the great wildlife events on earth, and it peaks now. At Ostional on the Nicoya peninsula, olive ridley turtles come ashore in mass synchronised nestings called arribadas – tens and sometimes hundreds of thousands of turtles over a few nights, several times a year, with the largest events usually in September and October.
- They cannot be predicted far ahead. Arribadas typically begin in the last quarter of the moon, but the exact nights are known only days in advance. You go and hope, or you stay nearby and wait.
- Access is controlled and a local guide is required. Ostional is a community-managed refuge.
- Getting there is harder in the rains – the roads to Ostional include river crossings that can become impassable.
Independence Day, 15 September
A national public holiday marking independence from Spain in 1821, and the most visible civic celebration of the Costa Rican year. In 2027 it falls on a Wednesday.
The night before, on the 14th, children across the country carry homemade faroles – paper lanterns, traditionally in the shape of an ox cart or a colonial house – in evening parades, and the national anthem is sung at 6pm. A Freedom Torch is relayed by schoolchildren on foot from Guatemala through Central America, arriving in Cartago on the evening of the 14th. The 15th brings school marching bands through every town.
Prices and crowds
The cheapest month of the year. Pacific rates bottom out – where businesses are open at all – and the Caribbean is good value despite being in its best weather. See what a trip to Costa Rica costs.
What to pack
A proper rain jacket and quick-drying clothes – September rain on the Pacific can last all day, unlike the afternoon pattern of May to August. Waterproof footwear, a dry bag, insect repellent. Expect mud.
The September 2027 calendar
- Through September – Pacific at its wettest, about 330 mm; Caribbean at its driest, about 160 mm.
- Through September – many Pacific lodges, operators and some park trails close for annual maintenance. Confirm before booking.
- Through September – olive ridley arribadas at Ostional, unpredictable and guided; largest events usually now or in October.
- Through September – green turtle nesting continues at Tortuguero; whale season still strong.
- Tuesday 14 September – faroles lantern parades in the evening; the Freedom Torch reaches Cartago.
- Wednesday 15 September – Independence Day, a national public holiday, with marching bands nationwide.
Read alongside
- Costa Rica in August – peak turtles and whales.
- Costa Rica in October – the same inversion continues.
- Costa Rica in November – the Pacific dries out again.
- Best time to visit Costa Rica – all twelve months compared.
- Costa Rica in 10 days – how the regions connect.
- Costa Rica travel guide – coasts, volcanoes and cloud forest.
- Trip to Costa Rica cost – the cheapest month of the year.
Frequently asked
Is September the worst month in Costa Rica?
Only on the Pacific, where it is the wettest month and many businesses close. On the Caribbean it is the best month of the year – the driest and sunniest.
Why is the Caribbean coast dry in September?
Because it runs on a different rainfall pattern from the Pacific, driven by the trade winds rather than the Pacific migration of the rain belt. September and October are its dry window while the Pacific floods.
Do things really close in September?
Yes. Many Pacific-side lodges, tour operators and restaurants shut entirely for annual maintenance in September and October, particularly around Manuel Antonio, Osa and the smaller Nicoya towns. Confirm your specific booking and park are open.
What is an arribada?
A mass synchronised nesting of olive ridley turtles – tens to hundreds of thousands coming ashore over a few nights. Ostional on Nicoya is the main site, and the largest events are usually in September and October.
Can you plan a trip around an arribada?
Not reliably. They generally start in the last quarter of the moon but the exact nights are known only days ahead. Access is controlled and a local guide is required.
What happens on 14 September in Costa Rica?
Children carry homemade faroles lanterns in evening parades and the national anthem is sung at 6pm, while the Freedom Torch relayed on foot from Guatemala arrives in Cartago. Independence Day itself is the 15th.
Is September cheap in Costa Rica?
It is the cheapest month of the year. Pacific rates bottom out and the Caribbean is good value despite being in its best weather.
Does it rain all day in September?
On the Pacific it can, unlike the afternoon-shower pattern of May to August. Pack for sustained rain rather than short downpours.
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Written by
John Morrison is the founder and lead travel writer at Packzup. Over the past decade he has explored destinations across Africa, the Americas, Asia, Europe, the Middle East, and Oceania — always self-funded, never on a press trip.
