How Much Will El Niño Affect Costa Rica?

And What Does It Mean for the Wildlife That Calls This Place Home?

Costa Rica is famous for its biodiversity. Monkeys and sloths in the rainforest, sea turtles nesting on our beaches, hundreds of bird species passing through. All of it depends on something most visitors never think about: the right combination of temperature, rainfall, and seasons arriving more or less when they are supposed to.

So what happens when those conditions change?

That is not a hypothetical question right now. It is happening.

What the Numbers Actually Say

El Niño is not coming. It is already here, and it is getting stronger. NOAA currently has an El Niño Advisory in effect, with a greater than 90 percent chance of a very strong event during the fall and winter of 2026 and 2027. Costa Rica's own Instituto Meteorológico Nacional projects that El Niño will reach "very strong" intensity between November 2026 and January 2027. NOAA Climate Prediction CenterInfobae

Here is what that has already meant on the ground. Between January and August of this year, the North Pacific region, which is Guanacaste, recorded a 37 percent rainfall deficit. The Central Pacific was down 28 percent, the South Pacific 25 percent, and the Central Valley 20 percent. On September 18th, the National Emergency Commission raised 23 cantons to orange alert, eleven of them in Guanacaste alone. InfobaeLaPatilla

And El Niño does not do the same thing everywhere. It dries out the Pacific side while increasing rainfall on the Caribbean side. This year the Northern Zone actually ran a small surplus and the Eastern Northern Zone came in 37 percent above normal. One country, two completely different stories, depending on which side of the mountains you are standing on. TeleticaInfobae

Climatologists have also pointed out a second effect that gets less attention: fewer hurricanes in the Caribbean means less moisture transported inland, which means less recharge for aquifers and reservoirs, at exactly the moment rainfall is already down. Acontecer

When the Ocean Changes, Wildlife Feels It

Recently, large numbers of pelagic crabs washed up dead along beaches in Guanacaste. Scientists found unusually warm water at depth off the coast. Several factors may have contributed, including ocean temperature, food availability, currents, wind, and waves.

No single definitive cause has been identified, and I want to be careful not to claim more than the science supports. But the event is still worth sitting with, because it points at something real: ocean temperature has consequences far beyond what we see on the surface. A change in temperature moves through plankton, then fish, then seabirds, then marine mammals. It moves up the whole chain.

The Sea Turtle Problem

Here is the example that gets me every time.

For most animals, sex is determined genetically. Sea turtles are different. For many turtle species, the temperature of the sand around the developing eggs is what determines whether the hatchlings come out male or female. Warmer sand generally produces more females, cooler sand produces more males.

Think about what that means in practice.

A mother turtle drags herself up a beach at night, digs a nest, lays her eggs, and returns to the ocean. She will never see them again. From that moment on, the temperature of the sand is writing the rest of the story.

Now put a hotter, drier season on top of that. Warmer sand. Lower humidity inside the nest. Longer stretches without rain to cool things down.

We are not just talking about weather anymore. We are talking about habitat.

Everything Is Connected

This is the part I love most about this country, and also the part that keeps me up at night.

You can look at a rainforest and see trees. You can look at the ocean and see waves. You can walk a beach and see turtle tracks. But none of those things are separate.

The trees hold the soil. The soil holds the water. The water feeds the rivers. The rivers feed the ocean. Rainfall and temperature drive the plants and insects. The plants and insects feed the birds and mammals. Pull hard enough on one thread and you feel it somewhere you were not looking.

A 37 percent rainfall deficit in Guanacaste is not just a number in a government bulletin. It is drier forest, stressed trees, less fruit, less water in the streams where animals drink, and hotter sand on the beaches where turtles nest.

So What Do We Do With This?

I am a tour guide, not a climate scientist, and I am not going to pretend one person can fix any of this.

But I do bring people into the rainforest for a living. Thousands of travelers come to Arenal, La Fortuna, Guanacaste, and Manuel Antonio every year specifically because they want to see what is here. That is a lot of people passing through. What if every one of those trips left something behind instead of just taking photos home?

So we are starting something simple.

One rainforest tour. One native tree.

For every rainforest tour we run, we plant one native tree. It is included in the tour, no extra cost, no upsell. Not for a photo op, but because a native tree eventually becomes food, shade, shelter, and habitat, and because in a drier climate the forest needs all the help it can get holding onto its soil and water.

For guests who want to do more than the one tree that comes with their tour, there is a voluntary donation option. That money goes toward native seeds and seedlings from local nurseries, planting materials, supplies to help young trees survive their first dry season, additional trees beyond the ones included, and the coordination and follow up of the planting areas themselves. That last part matters more than people realize. Planting is the easy day. Making sure the tree is still alive two years later is the work.

There is no pressure to donate, and there never will be. Your tree gets planted either way.

One Tree Is Not the Answer. It Is Just a Start.

Conservation does not have to begin with something enormous. Sometimes it begins with someone asking a question. Why did those crabs die? Why is it so dry this year? What happens to turtle eggs when the sand gets warmer?

And then maybe, after asking, planting something.

Costa Rica gave us an incredible natural inheritance. Let's enjoy it, let's learn from it, and let's leave a little more of it behind than we found.

🌱 Come explore Costa Rica with us. Plant a tree. Leave something growing behind.