CORVALLIS — Oregon, Idaho and Washington had their hottest Augusts in 128 years of record-keeping, the National Oceanic and Atmospheric Administration reported Friday, Sept. 9.

Heat records fell in all three states, topping old marks for the month by nearly a degree in Idaho and by more than a degree in Washington and Oregon.

Temperatures were far above normal. Idaho’s average temperature was 5.67 degrees Fahrenheit above the norm, while Washington’s was 6.3 and Oregon’s 6.6.

The three states also set records for average temperature over a two-month period, July and August. The Northwest has now had hotter-than-average summers for the past decade.

“The real story is that we have this big cluster of years with temperatures well above normal,” Oregon state climatologist Larry O’Neill said. “This is the kind of summer we’re expecting in the future. By 2050, this will be an average summer.”

California nearly set a heat record for August. Only August 2020 was hotter.

All four states also set records for August nighttime temperatures.

Washington state climatologist Nick Bond said greenhouse gases are holding in heat at night, keeping temperatures up.

“This is something we’re seeing more and more of,” he said. “It’s completely consistent with the physics.

“It’s like we have a thin film of clouds even when it’s clear,” Bond said. “In the morning, you’re starting off at a higher (temperature) level.”

Bond also noted there were few Pacific Ocean “weather disturbances” — the gentle summertime versions of storms — to usher in cool breezes and sprinkles of rain.

The hot summer came after an unusually wet and cold April, May and much of June.

Even after the fifth-hottest meteorological summer (June to August) on record, only 6% of Washington is classified as in a “moderate” drought by the U.S. Drought Monitor.

“My feeling is we should be grateful that last spring and early summer was as cool and wet as it was,” Bond said.

Oregon’s summer was the fourth-warmest on record, surpassed by three recent years, 2016, 2017 and 2021.

A warm north Pacific Ocean — reminiscent of “The Blob” that heated up the Northwest in 2013-15 — was another reason for the high temperatures, O’Neill said.

Warm and humid air flowed into Oregon and also trapped heat, he said, which “was definitely a factor.”

Sea-surface temperatures in the Gulf of Alaska and the Bering Sea remain well above normal, NOAA’s Climate Prediction Center reported Sept. 9.

Idaho had its sixth-warmest summer, and California had its third-warmest. Across the U.S., it was the eighth hottest August on record.

Rain varied more in the states. Washington had its 16th driest August, while Oregon had its 58th driest and Idaho its 69th driest. California had its 18th wettest August.