Costa Rica's Dry Season Is Only Dry in Half the Country

A chain of mountains runs down the country, and the two sides get their weather from different directions. The Pacific side has what travellers call a dry season. According to the climate page on Costa Rica's official tourism site, which follows the national weather institute's regions, it runs from December to March, with April as a transition month. March is the driest and hottest month. The rains return around May and are heaviest in September and October, with a short break in July and August that Costa Ricans call the veranillo, the little summer.

The Caribbean side has no such pattern. The same page says its climate "does not have a well-defined dry season" and that rain stays "between 100 and 200 mm in the driest months". It names two relatively drier spells, February to March and September to October, and puts the rainiest month in December. Weather aggregators we checked disagree on whether Limón's driest month is March or April, though both put it above 140 mm. Those are unofficial compilations, so read the figure as a scale and not as a normal. We could not read the weather institute's own regional documents, which its site links as PDFs.

For Arenal the useful question is not whether it will rain, but what you are buying when it does. Almost nothing on offer around La Fortuna depends on dry weather. Hanging bridges, hot springs, waterfalls and night walks all run in the wet, and rafting is the one activity that our category page says gets better in the rain. February to April are the better months in our grid because the cone is more often visible and the trails are firmer, not because the rain stops.

The second correction concerns the volcano itself. Arenal's last eruption ended in 2010, and the cone has been quiet since. Costa Rica's environment ministry has warned that climbing the cone is illegal, so no listing should sell a summit. Be careful with the words "red lava" as well. A few titles in any catalogue, ours included, use them for the trails across the lava rock left by the 1968 eruption. What those trails cross is cooled rock, fifty-eight years old.

Anyone who wants an erupting volcano in Central America should look at Guatemala instead and read the observatory's bulletin before booking. Costa Rica's remaining draws are crater lakes, fumaroles and mud, and that is plenty if it is what you came for.

San José is on the Pacific side of the divide, so its January is dry and its September is not. At 2,708 m, the Poás crater and its acid lake sit above the cloud base for only part of the day, and the summits are usually in cloud by afternoon. That is why the Poás and Irazú listings start early, and why the dry months matter less here than getting to the crater before the cloud arrives.

The harder constraint is access. Press reports say tickets for Poás are sold online only, through the national parks system, for a chosen date and time slot. They describe entries every 20 minutes, one of them putting the day at 08:00 to 14:00 with 19 groups. A separate report from a period of restrictions speaks of 56 people per shift and 20 minutes at the viewpoint. They describe different moments and we could not date either, so we do not print a rule.

Poás has also closed more than once for volcanic activity since 2025, and headlines run into 2026. We have not printed a current status, because it is the most perishable fact on this page. Read it on the day at the park system and the national observatory, and see how to check whether a volcano is erupting. Our page on what happens to a trip if the volcano erupts covers the booking side.

Rain is the variable everyone checks. Hours are the one that ends a day. Three of the four volcano areas below run on fixed slots or fixed days, and the park authority's own site returned a server error when we tried it, so everything in this table comes from Costa Rican press and guides. Treat it as a map of where to look, not as the schedule.

Two lessons come out of it. First, a Monday in Guanacaste is a different day from a Tuesday: the Pailas sector, the one in most day-trip listings, was reported shut on Mondays, so a Monday departure needs an operator who can name the sector it uses. Second, a first group at 05:00 and a last at 10:00 means that a late start at Turrialba loses the volcano, not an hour of it. Weather closures exist too. Costa Rican outlets reported in November 2024 that the parks system temporarily closed several protected areas for rain, among them both Rincón sectors.

If one trip has to include all three areas, February and March are the overlap. In our grid every area is at its best in at least one of the two, and the Pacific is still dry. That is also the answer for anyone reading this in November and planning ahead, which is the right time to book the Turrialba and Poás slots described above.

For a trip that leaves this month or next, the picture is more mixed. December is a worth-going month for Poás, Irazú and Rincón in our grid, but it is the rainiest month on the Caribbean side, so an Arenal-only trip in December is a wet one. Plan for rain, pick the activities that do not mind it, and keep the mornings for any volcano that needs a clear sky.

The wider picture, with 35 destinations and the physical reason behind each month, is on our when-to-go page. For the permit side of the same trips, see where you need a guide, a permit or both. The country's volcano areas are below, each with its own listings and its own calendar.