Portland, Oregon, soared to a searing 116 degrees Monday, hotter than it has ever been in cities such as Dallas, Los Angeles and New Orleans. In fact, when it comes to major U.S. cities, only Phoenix and Las Vegas have been hotter.
Meanwhile, a parallel heat wave was in full swing on the other side of the country, where Boston was forecast to touch 100 degrees Tuesday, with a forecast high of 98 degrees.
The culprit? A buckling in the jet stream causing amplified ridges to surge far north on both sides of the country, resulting in dangerous heat surging into areas unaccustomed to it. On Tuesday, 12 million Americans across much of the West were under heat watches and warnings, and 44 million were under heat alerts across the Northeast, stretching from Delaware up through Maine.
Monday was the textbook example of a summer scorcher, pumping heat into the entirety of the Pacific Northwest. More than 35 cities tied or set records, with many areas soaring an unprecedented 30 to 40 degrees above average. The record in Seattle was smashed by 5 degrees, establishing a new record of 108, and the record high in Portland was shattered, where the high temperature soared to a sizzling 116 degrees, 8 degrees higher than the old record.
The heat was so excessive that Portland streetcar power cables melted and the pavement buckled. And the heat has been so persistent that Seattle achieved a new record: three consecutive days of triple-digit temperatures for the first time.
The historic heat even jeopardized several state and national records. The record high of 119 for Oregon and the record of 118 in Washington came nearly within reach when Salem, Oregon, hit 117 and Dallesport, Washington, hit 118 Monday.
Most impressive, Lytton, British Columbia, recorded a high temperature of 118 degrees, establishing a new national record for Canada, and crushing the old record by 5 degrees. This temperature surpassed Las Vegas' all-time high of 117.
To put this extreme heat into perspective, the hottest temperatures in traditionally hot cities are still cooler than these new records for Portland and Seattle. Miami’s record high is a mere 100 and Atlanta's is only 106.
On Tuesday, the Northwest cities of Seattle, Portland, Boise, Idaho, Billings, Montana, and Reno, Nevada, are expected to continue to experience temperatures in the triple digits and the Pacific Northwest humidity will drive these temperatures to feel like the 110s.
In the Pacific Northwest, temperatures start to cool off Tuesday and Wednesday near the coast, but it will remain scorching hot in the interior, as the cooling breeze off the Pacific Ocean doesn’t reach sufficiently far inland. Tuesday will be the first day in three days that the forecast high is below 100 for Portland and Seattle, but temperatures will still remain in the 90s, 10 to 15 degrees above average. Glasgow and Helena, Montana, Boise and Spokane, Washington, can expect triple digits through the Fourth of July.
Daily records could even be broken across New England as temperatures are expected to feel well over 100.
Heat warnings cover much of New Jersey, and extend over Philadelphia. New York City will likely see its hottest temperatures so far this year, and Philadelphia and Boston have already declared heat emergencies. This is truly rare heat; New York City averages just a few days a year with temperatures above 95 degrees.
Temperatures moderate slightly through the end of the workweek, returning to about average by the weekend.
Summers are getting hotter in the Pacific Northwest as a result of climate change, with most cities feeling 2.5 to 3 degrees hotter than they did in 1970. As carbon dioxide levels continue to rise and climate change progresses, more extreme and more frequent heat waves can be expected for unprepared cities across the country.