Costa Rica in September: what to expect

September is the bottom of the green season on the Pacific and the top of the dry season on the Caribbean. The two coasts run on opposite patterns, and that single fact decides where you should sleep this month.

On the Pacific side — Guanacaste, Jacó, Manuel Antonio, Uvita, the Osa Peninsula — September and October are the wettest months of the year. Rain often arrives in the afternoon and can last into the night; some days are grey from morning. Rivers rise, dirt roads turn to mud and landslides can close mountain routes, so check conditions locally before driving. Corcovado and some Osa lodges reduce or close services around this period.

The Caribbean side — Puerto Viejo de Talamanca, Cahuita, Tortuguero — is at its driest in September and October, with more sun and fewer interruptions than any other month. This is the month to book the Caribbean and treat the Pacific as a short add-on at most.

The Central Valley and the mountains stay mild rather than hot: San José and the coffee towns sit around 18–26 °C, and Monteverde is cool, windy and misty, so a fleece earns its place in your bag. Arenal and La Fortuna get rain in any month; mornings are the clearest window for the volcano.

September is one of the quietest months of the year. Costa Rican school holidays are over, North American and European summer travel has ended, and the rain keeps the Pacific beach towns half empty. You will not queue for a zip line or struggle for a table.

Prices follow the crowds. This is low season almost everywhere: hotels, shuttles and tours commonly run at their cheapest rates of the year (2026 estimate), and walk-in bookings are usually possible. The exception is the Caribbean coast, where September is peak-quality weather and the better places in Puerto Viejo and Cahuita fill at weekends — book those ahead.

Two practical notes. First, some Pacific and Osa businesses close for annual maintenance in September and October, so confirm that your hotel and any boat tour are operating before you commit. Second, low season does not mean cheap flights: airfares track demand from your home country, not Costa Rican hotel rates.

The month's fixed point is Independence Day on 15 September. The celebration starts the evening before, on 14 September, with a torch relay that has run from Guatemala since the 1960s and lantern parades led by schoolchildren; towns across the country hold their own processions, and San José and Cartago are busy that night.

Expect small local fairs and civic events around the date rather than a large festival calendar. Public offices, banks and many shops close on 15 September, and buses run a reduced schedule, so plan travel for another day. Turtle nesting continues at Tortuguero into the autumn, and humpback whales are still being seen off the south Pacific coast through September and October, though sea conditions can limit boat trips — ask operators on the ground.

If you are in the Central Valley, this is also a good month for the covered markets and museums of San José and for the university district of San Pedro de Montes de Oca, where rain matters less than it does on a beach.

Build the trip around the Caribbean and the interior, and treat the Pacific as optional.

Base one: Puerto Viejo de Talamanca and Cahuita, for the best weather odds of the month — beaches, reef snorkelling and a laid-back town. Base two: Tortuguero, reached by boat or light aircraft, for canals and turtle nesting. Base three: the Central Valley — San José for museums and markets, San Pedro de Montes de Oca for food and student life, and day trips to Poás or Irazú when the morning is clear. Add La Fortuna if you want the volcano and hot springs, and accept that the cone may be in cloud.

Skip, or keep to a single night, the Pacific beach circuit: Manuel Antonio, Jacó, Uvita and the Osa are at their wettest and some services shut. If you have already booked the Pacific, front-load outdoor plans into the mornings and keep a covered backup — a coffee tour, a museum, a spa — for the afternoon.

Pack for warm rain, not for cold: quick-dry clothing, a light rain shell that packs small, sandals that survive mud and one pair of closed shoes for wet trails. A dry bag or a couple of zip pouches keeps phone and passport usable on boat transfers to Tortuguero.

Add insect repellent — mosquitoes are active in the wet season and dengue is present in Costa Rica — plus sunscreen, a refillable water bottle and a headlamp for early starts and turtle tours. For Monteverde and the highlands, bring a fleece or light jacket: evenings are cool and windy. If you plan to drive, download offline maps, since coverage drops on mountain routes.

August is similar but slightly drier on the Pacific and busier, with school holidays in some markets. October is the hardest month for the Pacific — heavier rain, more landslides and more closures — while the Caribbean stays dry, so it is a good choice only if you commit to that coast. November is a transition: Pacific rain eases and prices stay low, but the Caribbean turns wet.

If your dates are flexible and you want the classic Costa Rica trip — dry beaches, clear volcano views, easy driving — aim for December to April instead. If you are locked into September, the Caribbean plan below is the one that works.