Weathercatch: Summer arrived late. Then came a string of heat waves

The most unusual things about summer 2022 are how late it started, what happened when it finally arrived and how it ended.

Let us explain.

Remember damp and dreary June? The Inland Northwest typically enters the warm, dry season that month, but not this year. Instead, we saw unseasonably cool, wet conditions during the first two weeks. Heavy rainfall made it the all-time wettest June recorded for Pullman and the 11th wettest for Spokane. On June 13, not only did 0.72 inches of rain fall in the Spokane area (the average is 1.18 inches for the entire month), but the high temperature only reached 51 degrees, making it the coldest day of summer. Conditions were largely triggered by a plume of moisture caused by an atmospheric river that bore down on the Pacific Northwest. Atmospheric rivers generally occur in fall and winter, not June.

On June 22, the high temperature hit 80 degrees in Spokane for the first time in 2022. We typically see the first 80-degree day in mid-May. Summertime weather finally asserted itself on June 27, when Spokane reached a high of 93 degrees. The period of June 26-28 marked the first of five heat waves that baked the Inland Northwest during summer 2022.

That’s right. Five of them. The National Weather Service defines a heatwave as at least three consecutive days with 90-degree temperatures or higher. The first and mildest arrived at the end of June.

The most intense heatwave came next, spanning five days from July 25 to Aug.1. Spokane reached 102 degrees on July 29 and July 31, becoming the city’s two hottest days of summer. Elsewhere in the region, the Tri-Cities topped out at 112 degrees, Yakima 109 and Lewiston 108.

The third heat wave ran from Aug. 8-12, when Spokane reached a high of 96 degrees on Aug. 10, followed by an overnight low of 73 degrees, making it the hottest night of summer.

Heat wave No. 4 extended from Aug. 16-21, peaking at 100 degrees on Aug. 18, proceeded by another warm overnight low of 73 degrees.

Meteorological summer ended with the fifth and final heat wave that marched into early September. From Aug. 30 to Sept. 2, the Spokane area experienced four consecutive days of temperatures that ran 10 degrees or higher than normal. The hottest temperature reached 100 degrees on Aug. 31.

As you can see, four of the five heat waves occurred in August. Consequently, it became the hottest August recorded at Spokane International Airport in its 140-plus years of keeping weather data. The hot weather was mostly fueled by a sprawling and intense ridge of high pressure anchored over the West that trapped heat over our region.

And guess what? The ridging of high pressure is expected to stick around for a while. The September outlook from the National Oceanic and Atmospheric Administration’s Climate Prediction Center favors warmer-than-normal conditions in the Pacific Northwest with below-normal rainfall.

Nic Loyd is a meteorologist in Washington state. Linda Weiford is a writer in Moscow, Idaho, who’s also a weather geek. Contact: ldweiford@gmail.com.