A sign in the window of the Dick's Drive-In in Seattle's Capitol Hill neighborhood is shown Monday, June 28, 2021, in Seattle…
A sign in the window of the Dick's Drive-In in Seattle's Capitol Hill neighborhood is shown Monday, June 28, 2021, in Seattle. The walk- and drive-up restaurant, which is not air conditioned, closed early Sunday and all day Monday due to excessive heat.

The U.N. World Meteorological Organization (WMO) Tuesday called the heatwave hitting the Pacific Northwest corner of the United States “exceptional and dangerous,” and says it could last at least another five days. 

Speaking to reporters from Geneva, a WMO spokeswoman said while records have fallen in the U.S. states of Oregon and Washington, western Canada has seen extreme heat as well. 

Lytton, British Columbia, set Canada’s all-time high temperature Sunday with 46.6 degrees Celsius, only to see it broken less than 24 hours later, hitting 47.9 Celsius Monday.  

The official said the temperatures for this time of year and location are shocking. “It’s in the province of British Columbia, it’s to the Rocky Mountains, the Glacier National Park, and yet we’re seeing temperatures which are more typical of the Middle East or North Africa.” 

In an area used to temperatures 20- to 30 degrees cooler, the WMO said the extreme heat poses major health threats to residents as well as agriculture and the environment. 

People look for ways to cool off at Willow's Beach during the 'heat dome,' currently hovering over British Columbia and Alberta as record-setting breaking temperatures scorch the province and in Victoria, British Columbia, Canada, June 28, 2021.

The WMO said the extreme heat is caused by “an atmospheric blocking pattern,” which has led to a “heat dome” — a large area of high pressure — trapped by low pressure on either side. The organization said the temperatures would likely peak early this week on the coast and by the middle of the week in the interior of British Columbia; afterward, the baking heat is expected to move east toward Alberta. 

The U.S. National Weather Service in Portland, Oregon, on its Twitter account late Monday, reported cooler air was already in the region along the coastline. 

In a tweet Sunday, the Oregon Climate Service said the climate system is no longer in a balanced state, and such heat events “are becoming more frequent and intense, a trend projected to continue."