The temperature reached 108 degrees in the Tri-Cities, and today should be another scorcher, according to the National Weather Service.
The high today in the Tri-Cities is forecast at 103 degrees and highs are expected to remain above 100 through Wednesday as the Mid-Columbia endures one of its annual heat waves, the weather service said. The high in August in the Tri-Cities typically averages about 90 degrees.
With temperatures so hot, there's a risk of heat exhaustion even among healthy people who are playing or working outdoors, health officials warned. Symptoms include paleness, heavy sweating, weakness, dizziness, headache, vomiting or fainting, often with fast pulse rate and breathing.
People with those symptoms should find a cool place and rest, drink fluids and take a cool shower or bath. If symptoms are ignored, heat exhaustion can progress to heat stroke with the body unable to control its temperature, which is life-threatening.
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Despite the high temperatures, police across the Mid-Columbia reported few heat-related incidents Saturday.
The hot temperatures have raised fire danger throughout the Northwest, and Tuesday there's a slight chance of thunderstorms in the Tri-City area.
The weather service issued a red flag warning because of hot temperatures and extremely dry conditions in the Cascade Range in Washington and Oregon.
Olympic National Park plans to prohibit all backcountry campfires as of Monday because of the high fire danger.
Park Superintendent Karen Gustin says only campfires in established fire pits in "front-country" campgrounds will be allowed.
Park officials say six fires - all started by lightning - are burning in the park. The largest is the 350-acre Constance fire in the Dosewallips River drainage. On Saturday, 10 firefighters were assigned to that blaze, with helicopters dropping water on it.
Fire danger has prompted officials to close the popular Dosewallips trail from the western park boundary to the junction of Gray Wolf Pass and Dose Meadows trails, the Constance Pass trail, and the trail from Dose Forks to Honeymoon Meadows.
In Yakima County, firefighters contended with a lightning-sparked blaze near Rimrock Lake that had burned about 500 acres by Friday night.
Officials predict that blaze, called the Discovery fire, could be contained by Tuesday. About 245 personnel had been assigned to the blaze by Friday evening.
Randy Shepard, district ranger with the Naches Ranger District of the Wenatchee National Forest, told the Yakima Herald-Republic that the terrain's remoteness and steepness pose a challenge to firefighters. The majority of the fire is located on a heavily-timbered, west-facing slope.
"There are dead trees mixed with the live ones," Shepard said. "That could be dangerous. They're drier. They're more susceptible to catching fire.
"There's considerable potential up there for this fire to be rather severe."
The Ahtanum State Forest is also closed until further notice. While the area is not directly threatened, authorities said they would have a difficult time evacuating people if the Discovery fire made a run.
Other fires also were burning in Yakima County. A blaze erupted Friday near the community of Nile, east of Chinook Pass. Several small fires, started by lightning in the William O. Douglas Wilderness also were being monitored.
Authorities closed about a dozen trails in the vicinity of those fires.
No structure damages or injuries had been reported in any of the fires.
-- The Yakima Herald-Republic and Associated Press contributed to this report.
-- Annette Cary: 582-1533; firstname.lastname@example.org