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Northwestern US: Summer heat to surge back this week

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Memorial Day marks the unofficial start to summer, and elevated temperatures will waste no time in surging back into the northwestern United States this week.

After a mild and dry Memorial Day, warmth will build back across the Northwest Tuesday into Wednesday.

Further warming will likely yield the hottest weather so far this year toward and during next weekend with widespread records highs being challenged.

The impending heat will be a drastic change from what the Northwest has recently experienced.

"[Temperatures], the last 1-2 weeks have been near- to below-normal," AccuWeather Meteorologist Jim Andrews said. Seattle has not recorded a high above the 60s since May 13.

As a ridge of high pressure builds overhead, Andrews said that temperatures "will be off to the races" this week.

The initial surge of warmth Tuesday into Wednesday will cause temperatures to rise back into the lower 80s in Seattle. Temperatures will once again flirt with the 90-degree mark in Portland.

Between the two days, Tuesday will be the warmest for places toward the coast. Wednesday will bring significant warming east of the Cascade Mountains.

A pair of storm systems clipping the Northwest will briefly put the brakes on the warming trend around Thursday. However, it will still remain warm for early June. A couple of showers will also return to northwestern Washington.

However, the ignition switch for the heat will once again be turned on Friday and into next weekend as the jet stream lifts northward.

"Especially in the interior Northwest, we will be looking at record-challenging highs with 90s in the lower valleys and 80s in the higher valleys," Andrews said.

Yakima, Washington; Medford, Oregon; and Boise, Idaho, will even be near the century mark.

A wind off the Pacific Ocean will keep the immediate coast significantly cooler. A slight marine influence will also put a lid on the heat in Seattle, but temperatures should still climb to the lower 80s.

Residents can stay safe during the impending heat by drinking plenty of water, wearing light clothing and avoiding strenuous activity during the midday and afternoon hours (the hottest times of the day). Take frequent breaks if the latter cannot be avoid.

"[The warmth] will renew the spring thaw in the mountains," Andrews said. "That will swell streams that drain out of the higher mountains."

Residents should also resist the urge to jump into these streams as the water will be dangerously cold.

"This week will also be a dry time, so the region will dry out and increase the fire danger," Andrews said.

Thunderstorms sparking wildfires will be limited but could increase toward the end of next weekend if a new system tracks inland and cuts into the heat.