A heat wave is forecast with record temperatures in areas of the northeastern US where many people do not have air conditioning.

(CNN Spanish) – An extraordinary heat wave is forecast for this weekend, potentially unlike any the northwestern United States has experienced.

As temperatures reach and exceed 38 degrees Celsius, Seattle could feel like Las Vegas, while Portland could experience Phoenix’s level of heat, in an area where having air conditioning is not always the norm. Dozens of heat records are forecast to be broken in Oregon, Washington and Idaho, even beating some all-time records set decades ago. And all during the first weekend of summer.

“Usually the hottest time of year (in Washington) comes a month after the solstice,” Rocco Pelatti, a meteorologist with the National Weather Service in Spokane, told CNN Weather. “July is generally the hottest month, sometimes it extends into August. That June begins as it has is very worrying.

In Seattle and Portland, the heat will reach levels previously unknown. By the end of the weekend, high temperatures could be 12.5 to 15 degrees Celsius above normal for this time of year.

Seattle’s average high temperature in late June is 22 degrees, while Portland is generally around 24 degrees in the afternoon at this time of year. However, forecasts suggest that high temperatures could be near or above 37.8 degrees in the two cities from Saturday to Monday.

Seattle has temperature records since 1894, and during that time, it has surpassed the 37.8 degrees Celsius mark only three times.

The temperature in Seattle rarely rises above 32 degrees. As a result, the highest temperature ever seen in June at Seattle-Tacoma International Airport (35.5 degrees in 2017) could also be exceeded this weekend.

As with last week’s Southwest heat wave, a huge high pressure ridge – colloquially known as a heat dome – will be responsible for the torrid heat. But unlike the Southwest, millions of people in the Northwest do not have air conditioning in their homes.

“In this area, not many people have air conditioning, so we don’t have the relief that can be found in other places that get this hot,” explained Mary Butwin, a meteorologist at NWS Seattle.

The city with the least air conditioners in the United States

The heat could be deadly in Seattle and Portland, which rank first and third respectively among major cities in the United States with the fewest air-conditioned homes. A study The 2015 Census Bureau found that only 33% of Seattle-area homes had air conditioning.

Historically, the lack of air conditioning in Seattle – a city known for its warm summers – has not been a problem. Between 1971 and 2000, the city averaged just three 32-degree days each summer. However, from 2015 to 2018, the average number of 32 degree days jumped to 10 each summer.

Since most homes in western WA don’t have central AC, here are a few tips on how to keep your home cool this coming weekend. #wawx pic.twitter.com/ILcoCn1mBh

– NWS Seattle (@NWSSeattle) June 23, 2021

Not surprisingly, the Census Bureau updated its findings in 2019, when it reported that the addition of air conditioners had risen to 44%. This implies an 11% rise in air conditioning units installed since 2015.

“What makes this heat wave unique compared to others we’ve had in the area is the lack of marine influence in the evening hours,” said NWS Seattle meteorologist Samantha Borth.

With its proximity to the Puget Sound and the Pacific Ocean, nighttime temperatures can drop to around 10 degrees, even on the hottest days of summer.

Since searches began at Sea-Tac Airport in 1945, there was only one night that did not drop below 21 degrees: the morning of a nearly 40 degree afternoon in July 2009. On Sunday and Monday, the searches could arrive to include two more mornings with temperatures around 21 degrees, making it an unbearable weekend for homes without air conditioning.

Historical records could be broken

An even more oppressive heat wave is brewing in Portland.

The highest temperature that the city reached in a month of June was 16.6 degrees on June 26, 2006. The maximum temperature that it registered in all its history was a little higher, 41.6 degrees (in August 1981 and July 1964).

From Saturday to Monday, forecasts point to high temperatures in the range of 37.8 to 43.3 degrees in Portland. They will likely break the historic June mark and threaten to hit the city’s historic high temperature.

As the high pressure dome strengthens, the air is compressed and the temperature rises, like the heat felt in a bicycle pump while inflating a tire. That, combined with dry winds from the eastern deserts of Washington and Oregon, could potentially set records for both states.

In Spokane, temperatures are likely to top 37.8 degrees well into next week.

“We haven’t seen anything like this in a long time,” says Pelatti. “For the Spokane area, we forecast 42 degrees for Monday and Tuesday. Even after Tuesday, it still looks like it will continue to be very hot, with temperatures above 37.8 degrees.

The last time Spokane recorded consecutive days above that threshold was in 1928.

Like Washington and Oregon, Idaho will have record heat levels through next week.

“Right now, we’re seeing 40.5 to 43 degrees in the Serpent River basin of Idaho and the Treasury Valley,” said Korri Anderson, a meteorologist at NWS in Boise. “We could break all-time records in Boise on Tuesday and Wednesday of next week.”

The all-time high in Boise is nearly 44 degrees and Ontario is 45, Anderson added. “We could be flirting with that number next week.”

An excessive heat alert was issued for more than 11 million people in parts of Washington, Oregon and Idaho. In the Columbia basin, the region’s usual heat source, the forecast indicates that the high temperature this weekend will be between 43 and just over 44 degrees.

These temperatures would be a surprising distance from the state records for Oregon (47.2 degrees in July 1939) and Washington (47.7 in August 1961).

Extreme heat will become the norm in the Northwest

In some parts of the Northwest, the average number of days with temperatures of 40.5 degrees could go from 0 to 2 in just 15 years, according to a study recent.

Without any intervention, that number would increase to an average of five days by the end of the century, while 32 degree days would increase from about six to 37 days each year in that same period.

“There is always the likelihood of extreme heat, particularly in the summer,” Katharine Hayhoe, chief scientist at the Nature Conservancy, previously told CNN. “But as the world warms, we see that summer heat waves arrive earlier, last longer, and become hotter and more intense.”