The heat wave has begun.
High temperatures into the 80s and low 90s in Western Washington are forecast through Wednesday, and the National Weather Service predicted lows at night in the mid- to high 60s, offering little relief.
The multiday heat event will increase fire risk, too, and a red flag warning was issued in the Cascades due to low humidity and unstable conditions, meaning any fires that develop could spread quickly. Breezy northerly winds increase concerns, as well.
Outdoor burning is not recommended. All it takes is one spark to start a brush fire, said NWS meteorologist Steve Reedy
Major heat risk is expected through Tuesday, posing a threat to anyone without effective cooling or adequate hydration. A strong ridge of high pressure and surface winds coming from Eastern Washington are limiting the usual cooling marine influence, Reedy said. North Bend was forecast to potentially hit a high above 100 degrees Monday afternoon.
Symptoms of heat exhaustion include dizziness, thirst, heavy sweating and nausea. Signs of heat stroke include confusion or becoming unconscious, and emergency treatment is needed.
Moderate air quality was measured along the Interstate 5 corridor Sunday afternoon as smoke from the Sourdough fire in the North Cascades wafted west — which is why many may have awakened Sunday to the smell of smoke outside. The smoke is likely to stick around until at least midweek.
Crews fighting the Sourdough fire conducted successful burnout operations on the southwest flank of the fire Saturday to control the rate it's consuming fuel. Firefighters are monitoring the results of the burnout operations above Highway 20, but risk increased Sunday morning due to the heat. The highway remains closed from milepost 120 in Newhalem to milepost 146 east of Granite Creek.
Cooling will begin Thursday, but the National Weather Service remains uncertain about exact temperatures.
"It'll be rough, but there is relief on the way," Reedy said.
