Amber warning: Extreme heat forecast in United Kingdom, Western Europe

WEATHER NEWS: Amber warning: Extreme heat forecast in United Kingdom, Western Europe


The United Kingdom is bracing for sweltering temperatures late this weekend into early next week, with widespread highs between 90 and 95 degrees (32 to 35 Celsius) and a few spots potentially nicking 100 (38 Celsius). The U.K. Met Office has issued extreme heat alerts — or amber warnings — for much of England and parts of Wales, where temperatures could approach all-time highs.

Extreme heat has already spread over Portugal, Spain and France, where highs have reached the triple digits, and the worst is yet to come. Heat index values, which factor in humidity, could top 115 degrees (46 Celsius). In an unprecedented situation, all of mainland Portugal is under a red weather warning due to the hot temperatures, increasing the risk of wildfires across the country.

The amber warning in the U.K. includes London, which is bracing for highs above 90 degrees (32 Celsius) by Monday. While that may not sound hot by U.S. standards, Craig Snell, a forecaster at the Met Office, said that’s about 18 degrees (10 Celsius) higher than London’s average mid-July high temperature.

“We have a big pool of warm air across Spain and Portugal at the moment. As we go into Sunday, a door will open and it will shoot its way to the U.K., giving the already warm U.K. a boost,” Snell said.

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The highest recorded temperature for the U.K. is 101.7 degrees (38.7 Celsius), which was set in Cambridge in 2019. Snell said there was a 30 percent chance that this record could be broken.

This is the second instance of excessive heat blasting Western Europe in recent weeks as human-caused climate change fuels higher temperatures.

Portugal, Spain and France

Portugal, Spain and France face a prolonged bout of unusually high temperature, which began early this week.

In France, the heat will last until Tuesday. Thirty-one departments across the nation are under some form of heat alerts, and the government is reactivating a phone helpline for residents with questions or concerns about the heat.

“The thermometer is soaring this afternoon,” Météo-France, the country’s equivalent of the National Weather Service, wrote in an online forecast discussion Tuesday. “It displays 23 to 28 degrees [73 to 82 Fahrenheit] on the Channel coast, but everywhere else the highs are generally between 32 and 36 degrees [89.6 to 96.8 Fahrenheit], with locally up to 37/38 degrees [99 to 100 Fahrenheit] in the South- west and in the middle of the Rhone valley. The heat wave will last several days in the south of the country.”

In the Rhone Valley, temperatures over the next several days could reach 104 degrees (40 Celsius). In Paris, highs could surge well into the 90s by early next week, while the average high is closer to 77 (25 Celsius). forecasts a high of 100 degrees (38 Celsius) on Tuesday.

The island of Yeu off the west coast of France on Monday tied a record for its hottest temperature ever recorded, having spiked to 95.4 degrees (35.2 Celsius)

Sixteen out of 18 districts in Portugal are under top-tier red heat alerts; the two remaining are under a yellow or orange alert. Lousã, a town in central Portugal, set an all-time high of 115.3 degrees (46.3 Celsius) Wednesday. The hottest temperature ever recorded in the country was 117.3 degrees in Amareleja on Aug. 1, 2003.

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In Spain, an “extreme risk” of heat has warranted a red alert to be issued Wednesday for Campiña Sevillana and Vegas de Guadiana, where maximum temperatures were predicted to peak at 44 degrees Celsius (111 Fahrenheit). Spain has 50 provinces; the remaining are mostly under orange “important” heat alerts and lesser yellow alerts.

In Madrid, the high is forecast to hover near record levels or around 105 degrees (41 Celsius) through the weekend.

It will take until late in the weekend or early next week for the heat to reach the U.K.

“From Sunday, but more likely Monday, peak maximum temperatures could be in excess of 35C [95 Fahrenheit], most likely central and southeast England. Elsewhere, maxima will generally range from high 20s to low 30s of Celsius [80 to 90 Fahrenheit],” Met Office deputy chief meteorologist Dan Harris said in a news release. calls for London to hit 90 on Monday and 95 on Tuesday.

Some places, including downtown London, won’t see lows dipping below 70 degrees (21 Celsius) at night. Coming off a day in the 90s, that translates to homes that may struggle to fall below 75 or 80 degrees (24 or 27 Celsius), particularly since very few U.K. households have air conditioning.

“Population-wide adverse health effects are likely to be experienced, not limited to those most vulnerable to extreme heat, leading to potential serious illness or danger to life,” the Met Office wrote in its warning.

A few computer models have simulated temperatures as high as 104 degrees (40 Celsius) in the U.K., which would shatter its all-time record, but the Met Office notes that potential has waned some.

“Some models had been producing maximum temperatures in excess of 40C [104 degrees Fahrenheit] in parts of the UK over the coming weekend and beyond,” Harris said in the Met Office’s news release. “Recent evidence suggests the chances have decreased.”

Still, he added, a few locations could see highs in the upper 30s Celsius, or either side of 100 degrees Fahrenheit.

The heat will ease over the U.K. and France by the middle of next week but spread into Central Europe, scorching Germany, Switzerland, Poland, Austria and the Czech Republic on Wednesday and Thursday.

What’s causing the heat?

Instigating the heat is something called a “cutoff low,” or a low-pressure system that has become pinched off from the jet stream. It’s analogous to paddling a boat through a pond and watching a whirlpool shed off the oar and continue spinning aimlessly. In this case, the low is a self-sustaining swirl of counterclockwise-spinning winds wrapped about a lobe of high-altitude cold that’s whirring around a few hundred miles southwest of Portugal over the open northeast Atlantic.

Because it’s no longer nestled within a dip in the jet stream and subsequently shuttled west to east, there’s nothing to really scoot it along. As a result, the cutoff low will spend days sitting in place and spinning, with southerly winds on the eastern side of the system pumping African heat northward toward Western Europe and the U.K.

While the heat will gradually ease from west to east in Europe next week, it marks the latest in several European heat events that have been exacerbated by human-induced climate change. While human influence is not the cause of the hot weather, it tips the scales toward more frequent, intense and prolonged heat waves.

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It has been just over three years since an unprecedented heat wave baked Europe, sending temperatures skyrocketing. Paris hit an all-time high of 109 degrees (42.8 Celsius). Last month, a heat wave set hundreds of records throughout Europe.

Snell said the Met Office tracks how many years the U.K. has reached 35 Celsius (95 Fahrenheit) on a single day. Since the 1970s, this has happened nine times — four of which were in the past decade. “It shows how the frequency of hot weather in U.K. is increasing,” he said. “The frequency of these hot spells across Western Europe will increase as climate change continues.”

Karla Adam reported from London.

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