April Temperatures Hit Joint Third-Highest on Record Globally As Chance of Very Strong El Niño Grows

Unusually high temperatures persisted well into April, with record high averages across large parts of the tropical Pacific and near-record sea surface temperatures, according to the European Union Copernicus Climate Change Service. 

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Last month was the joint third-warmest April on record, with temperatures 1.43C above pre-industrial levels, the European Union’s Earth Observation program Copernicus has confirmed.

The month continued the streak of extreme global warmth seen in recent months, with December, January, and February each ranking as the fifth-warmest for their respective months, and March as the fourth-warmest March globally. Amid this sustained global heat, scientists at the National Oceanic and Atmospheric Administration (NOAA) said it is “virtually certain” that 2026 will rank among the 10 warmest years ever recorded, with the year also on pace to finish among the top five warmest on record.

Meanwhile, the average sea ice extent was about 5% below average. It was the second-lowest extent ever recorded for the month, Copernicus said. 

On the opposite pole, the trend was exactly the same, albeit less striking. In the Antarctic, the monthly sea ice extent was about 10% below the April average, ranking as the eleventh lowest for the month, and close to values observed in the past two years. The Bellingshausen Sea, located along the west side of the Antarctic Peninsula, was particularly affected, remaining “virtually ice-free.”

Sea surface Temperatures Near Record Highs

Sea surface temperatures approached historic highs once more in April, particularly across the extra-polar oceans, which saw their second-highest temperatures on record. More broadly, exceptionally warm waters stretched from the central equatorial Pacific to the western coast of the US and Mexico, corresponding to “strong” marine heatwave conditions, Copernicus said in its monthly bulletin. 

“April 2026 adds to the clear signal of sustained global warmth with sea surface temperatures near record levels and widespread marine heatwaves,” said Samantha Burgess, Strategic Lead for Climate at the European Centre for Medium-Range Weather Forecasts. 

El Niño Looms

The unusual warming of global seas is the “hallmark” of an emerging El Niño, a global climatic phenomenon which occurs every two to seven years, on average.

El Niño is associated with the warming of sea-surface temperatures in the central and eastern tropical Pacific Ocean. When this happens, the east-to-west trade winds die, keeping warmer than the normal air in the eastern and central parts of the tropical Pacific. Besides increasing temperatures, this also brings opposing weather patterns around the world, such as severe droughts in places like Australia and Southeast Asia and heavy floods in parts of the US and East Africa. 

Already in March, weather forecasters including NOAA predicted a high chance of an El Niño event developing later this year. Several forecasters have since updated their predictions, suggesting that this year’s event could become one of the strongest ever. Such an outcome could amplify extreme weather worldwide, and potentially qualify as a “super” El Niño, which is declared when water temperatures in the equatorial Pacific rise more than 2C above average, but uncertainty over its peak strength remains high.

Importantly, as NOAA notes, stronger El Niño events do not always mean bigger weather and climate impacts; they can only make certain impacts more likely.

The last major event, in 2024, coincided with the hottest year ever recorded and instigated severe droughts worldwide. This year is forecast to rank among the five warmest on record. However, this projection does not account for the possible development of a major El Niño event. If it occurs, the combination could further propel global temperatures upward and potentially make 2026 one the hottest years ever recorded and even boost 2027’s temperatures to record highs.