El Niño and La Niña in Costa Rica
🌊 El Niño & La Niña: The Engines of Our Costa Rican Climates
Costa Rica’s climate is shaped by the El Niño–Southern Oscillation (ENSO), a recurring cycle that includes El Niño, La Niña, and neutral phases (La Nada). These patterns influence rainfall, temperature, and seasonal timing across the country.
El Niño often brings drought and heat, while La Niña tends to increase rainfall and flooding. This is a general approximation as the exact effects depend on the time of year and other factors. Both phases affect agriculture, energy production, tourism, and infrastructure. This article explores ENSO and how it impacts Costa Rica.
🔥☀️ El Niño: Drought, Disruption, and Dry Season Intensification
El Niño warms the central and eastern Pacific Ocean. In Costa Rica, this typically means:
- Drier conditions on the Pacific coast and in the Central Valley
- Reduced rainfall during the rainy season (May–November)
- Increased risk of wildfires especially in Guanacaste
- Lower reservoir levels threatening hydroelectric power generation
- Crop stress especially for coffee, sugarcane, and rice
- Tourism volatility with water shortages and heat waves affecting travel plans
The 2015–2016 El Niño triggered one of Costa Rica’s worst droughts in decades. In 2023, another El Niño phase led to critical water deficits, nearly forcing electricity rationing due to low hydroelectric output.
❄️⛈️ La Niña: Rainfall Surges and Widespread Flooding
La Niña cools Pacific waters and flips the pattern:
- Increased rainfall on the Pacific side
- Flooding risk in low-lying areas and river basins
- Drier conditions on the Caribbean slope
- Improved crop yields in some regions, but soil erosion in others
- Strain on infrastructure especially roads and drainage systems
In 2017, La Niña contributed to widespread flooding, damaging homes and disrupting transport. Lasting almost 3 years, the 2020-2023 La Niña was especially long. The usual timeframe for La Niña is between 9 to 12 months.
🌀🫤 La Nada: The Unpredictable Middle Ground
When neither El Niño nor La Niña dominates, Costa Rica enters the funnily named La Nada. This phase is marked by:
- Unpredictable weather—sometimes extremely wet, sometimes unusually dry
- Difficulty in long-term planning, especially for farmers and energy providers
- Increased vulnerability to sudden climate shifts
La Nada challenges Costa Rica’s forecasting systems. Without clear patterns, communities must rely on real-time data and flexible strategies.
❄️🔥 A BIG Variation in Ocean Temperatures!
These two global maps, below, compare sea surface temperature anomalies during La Niña (2011) and El Niño (2016). Both focus on the Pacific Ocean, where ENSO events originate. Each black oval marks the core zone of temperature change.
The top map shows cooler-than-average waters in the central and eastern Pacific, shaded in blue. This cooling defines La Niña conditions.
The bottom map highlights warmer-than-average waters in the same region, shaded in red. This warming signals El Niño.
💃🏼🕺🏼 A Never-Ending Dance
Back-and-Forth we go – as the Pacific temperatures dance around the averages. The warmings & coolings may be severe or gentle. They can last a long time or be very brief; and sometimes there are consecutive series of warmings or coolings. But, overall, the Back-and-Forth pattern is pronounced.
💨🍃 What Causes the Ocean Temperature Variations?
The El Niño–Southern Oscillation (ENSO) is caused by dynamic interactions between the ocean and atmosphere across the tropical Pacific. These feedback loops between ocean temperatures, wind patterns, and atmospheric pressure create the irregular ENSO cycle and dramatically reshapes global weather, ecosystems, and economies every few years. At its core, ENSO arises from fluctuations in trade winds which normally blow westward and pile warm surface water near Indonesia.
El Niño
When these winds weaken, as in El Niño, warm water shifts eastward toward South America, disrupting the usual upwelling of cold, nutrient-rich water. The atmospheric response to these ocean changes involves a breakdown or reversal of the Walker Circulation, a system of rising and sinking air that governs tropical rainfall.
La Niña
During La Niña, the opposite occurs: stronger trade winds intensify upwelling, cooling the eastern Pacific and reinforcing the Walker Circulation.
The Back-and-Forth
📖 🤓 Further Reading
You may be interested in our three other climate-related articles (click to link):
- The Intertropical Convergence Zone (ITCZ)
- The EIGHT Climates of Costa Rica
- Why So Few Hurricanes Hit Costa Rica
The oscillating weather patterns affect every part of the world, even locations far away from the tropics. In Costa Rica, we have learned to live with the ebbs and flows of tropical climates. We always welcome the sun. And are equally happy to see a decent deluge freshen up the rainforests and provide welcome relief. PURA VIDA, as they say! Come and experience our amazing tropics – visit our RE/MAX WE SELL PARADISE website to view the hot properties in our local area.
