A deadly heatwave slowly simmering in Western Europe this month is being driven by a weather pattern known as the omega block, which scientists say could become more common around the world — including Canada.
The heatwave pushed temperatures up to 18 degrees Celsius above their seasonal average, according to the Reuters Climate Observatory. Hundreds of people have died, including at least 40 in France, who drowned while swimming to escape the heat, according to officials.
“In the region studied, this heat wave is the most intense ever recorded,” the global group of climate scientists said in a report. Friday analysis.
Here’s what to know about the omega block, and whether climate change is to blame.
The omega block gets its name from how pressure systems appear on a weather map, which resemble the Greek letter “Ω.”
In the case of Europe, a wave of warmer high pressure has settled over the affected countries, with low pressures on either side of it – the Atlantic coast to the west, and parts of Eastern Europe at the opposite end.
Warm air gets trapped or “clogged” inside this structure, unlike normal conditions where the jet stream carries weather systems from west to east.
“Because you have that high-pressure system in the center, you have a very stable, very warm air mass because the heat is moving northward into that area,” Gordon McBain, professor emeritus of weather and environmental studies at Western University, said in an interview.
“It then builds up over time.”
Omega blocks usually last between three to 10 days, but can sometimes last for weeks.
A map showing the maximum temperatures expected during the period from June 25 to 27 in Europe.
news agency
What happens during an omega block?
Countries including Spain, France and Germany are experiencing hot and dry conditions. Since high pressure also prevents cloud formation, there was little respite from the sun.
France recorded its highest ever temperature of 43.8 degrees Celsius in the small town of Bessos in the southwest of the country on Wednesday.
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That day was the hottest day in the entire country on record, according to French weather agency Meteo France, which said the average temperature measured at 30 French weather stations across day and night reached 30 degrees Celsius for the first time ever.
The German city of Saarbrücken, near the French border, broke the national temperature record on Friday at 41.3 degrees Celsius.
Meanwhile, areas located in areas of low pressure surrounded by the heatwave are likely to see cooler and rainier conditions.
Britain was caught in the middle of high and low pressure systems, with intense heat in the south and east and cooler temperatures in the north and west, according to the UK Met Office.
However, meteorologists extended the red heat alert on Friday after the temperature in Suffolk, England, reached 37.3 degrees Celsius, marking the hottest June day the country has ever seen.
Could the omega block occur in Canada?
Yes, this actually happened this year.
say meteorologists at The Weather Network The Omega Block was responsible for a late May heat wave in parts of Alberta, Saskatchewan and Manitoba. Most of the region saw highs reaching 35 degrees Celsius.
Another omega block was also behind the record high of 21 degrees Celsius set in Saskatchewan in January 2024. Network said.
Omega blocks can be predicted with fairly high confidence before they happen, McBain said, noting that they are one of several extreme weather patterns that have become more frequent in recent years.
What role does climate change play?
The World Weather Attribution analysis said a European heatwave would have been “almost impossible” without human-caused climate change.
Scientists said that a similar heat wave that occurred in the same month 50 years ago would have been about 3.5 degrees Celsius cooler than this one.
The analysis added that high nighttime temperatures over the past week were 100 times more likely than they were two decades ago.
This is due to a rise in global temperature baselines made possible by greenhouse gas emissions.
The European heatwave also occurs on the fifth anniversary of the deadly heat dome that scorched British Columbia and the U.S. Pacific Northwest in 2021, which saw more than 600 people die in the province alone.
McBean said it’s important for people and officials to be aware of the increasing frequency of such heat events and prepare accordingly.
He said: “These are conditions that unfortunately lead to death (and) significant economic costs, and these costs will increase in the future.”
“We need to adapt our ways of dealing with it,” he added, from improved alarm systems to ensuring homes and buildings are designed with cooling in mind.
—With files from The Associated Press and Reuters
&Copy 2026 Global News, a division of Corus Entertainment Inc.
