Gulf of Panama Upwelling Watch
In 2025 the seasonal upwelling that normally dominates the Gulf of Panama failed. It was the first failure in more than forty years of records.
Upwelling brings cool, nutrient-rich water into the sunlit surface layers of the Gulf. The production that follows supports Panama's largest fishery.
Until then the upwelling had arrived every year on record. We reported the failure in PNAS and have monitored the Gulf since, through the return of upwelling in 2026.
NOAA forecasts that the Pacific may now be entering the strongest El Niño since records began in 1950. This page reports what we measure before and through the 2027 upwelling season.
Surface water in the Gulf is warm and water at depth is warmer still. Surface heating does not warm water at depth, so the heat has arrived from elsewhere. The cold, low-oxygen water that normally sits at depth through the rainy season is absent. A strong El Niño is moving in from the west.
The coming season
The hypotheses
Every January the trade winds cross the isthmus of Panama and push surface water out of the Gulf. Cold, nutrient-rich water rises to replace it. For three months the Gulf is among the most productive tropical waters anywhere. Panama's fisheries depend on it. In 2025 the upwelling failed for the first time in more than forty years of records.
In 2026 it returned strongly. A strong El Niño is now pushing warm water east across the Pacific in a series of Kelvin waves. These waves depress the boundary between the warm surface water and the cold water beneath. The next season begins in January. We expect one of three outcomes.
A. Upwelling suppressed
The warm layer thickens until the cold water lies deeper than the winds can draw from. Strong winds blow, unlike 2025, but no cold water reaches the surface. This is the classic El Niño suppression described off Peru.
B. Upwelling of warm water
Upwelling is strong, but the water that rises is the warm, nutrient-poor water carried east by the Kelvin waves. Production falls. We suspect this has happened before and has never been documented.
C. An ordinary season
The wind-driven system overrides the El Niño signal and the Gulf behaves normally. Cold, nutrient-rich water reaches the surface and phytoplankton blooms follow. No one has measured a normal season under these conditions.
Latest update
—
—Earlier updates
Full water column
Anomaly through the whole water column
Methods
Where these numbers come from
- Weekly profiles
- A multiparameter sonde lowered through the water column at seven stations across the Bay of Panama. This page uses stations 3, 4 and 5, the deepest and most consistently sampled, which reach 54, 50 and 41 metres.
- Record
- Continuous since July 2017, roughly weekly, with a gap through 2020. The figures here rest on — casts.
- Baseline
- Anomalies are against 2018–2024, week by week and depth by depth, and are leave-one-out, so no year is ever compared against itself.
- Data
- The underlying series are published by the STRI Physical Monitoring Program.
Contacts