Scientists say jet stream block, not El Nino, drives Europe’s deadly heatwave

As a deadly heatwave continues to grip Western Europe, with temperatures soaring more than 18°C above seasonal norms and at least 50 fatalities reported in France alone, climate scientists are pushing back against media narratives linking the extreme heat to the developing El Niño in the Pacific Ocean.reuters+1

The Omega Block Mechanism

The current heatwave is being driven by an atmospheric phenomenon known as an "Omega block" — a jet stream pattern resembling the Greek letter Ω that traps a dome of high pressure over a region for extended periods while cooler weather prevails at its flanks. Britain recorded its hottest June temperature on record at 36.1°C, France logged its highest average temperature ever on Tuesday, and Italy issued its maximum heat alert for 16 cities including Rome, Milan, and Florence.reuters+2

Ioanna Vergini, founder and chief weather analyst at the global forecasting platform WYF24, said the attribution to El Niño is misplaced. "The Pacific is not currently in a strong El Niño state, and even when it is, its direct influence on European summer heat is weak and poorly delineated," Vergini said, according to reporting by Antena3. She described the event as "a classic jet-stream blocking phenomenon acting on a record-warm background. The heat dome is the mechanism; long-term warming is the amplifier; El Niño is a red herring."antena3

Corroboration From U.S. Forecasters

Jon Gottschalck, a meteorologist at the U.S. Climate Prediction Center, offered a similar assessment during the May heatwave that preceded the current event, telling USA Today that the heat in Europe was "attributed to an ongoing atmospheric blocking pattern rather than the El Niño Southern Oscillation."usatoday

The World Meteorological Organization reported in early June that there is an 80% probability of a moderate-to-strong El Niño developing between June and August, which could elevate global temperatures in the months ahead. However, experts stress that this broader warming signal is distinct from the regional blocking pattern currently responsible for Europe's extreme heat.dw

A Continent Under Strain

The heatwave, Europe's second heat dome event in just two months, has forced hundreds of school closures, triggered power grid disruptions across France, and prompted red weather warnings in Britain, France, Spain, Italy, Germany, and Switzerland. Forecasters warn conditions may worsen through the weekend, with temperatures in parts of France and Iberia expected to remain in the low-to-mid 40s Celsius.severe-weather+2

Scientists note that while climate change is not the direct cause of any single blocking event, long-term warming raises the baseline on which such events operate — making each heatwave hotter and more dangerous than it would have been decades ago.cnbc+1