What to know as Western Washington enters heat wave this week

With temperatures slated to reach into the 90s, Western Washington is under a heat advisory until 11 p.m. Wednesday evening.

The heat wave will span Monday, Tuesday, and Wednesday, with overnight lows struggling to dip into the 70s. Temperatures are expected to lower into the high 80s Thursday, and potentially down into the 70s by Friday.

"We haven't had an extended stretch of heat like this so far, especially with the very warm overnight lows," said National Weather Service meteorologist Matthew Cullen. "It will be really critical to stay hydrated. Get some cool air if you can, whether it's air conditioning at your home, if you have that. If you don't, finding a cool spot for at least a couple hours during the day. That really makes a big difference in terms of health."

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"It will again be quite warm tonight," Cullen added. "It's the accumulation of heat that concerns us. The one hot day by itself isn't necessarily problematic for a lot of folks, as long as you take precautions. But the longer this draws out, that's where heat really starts to impact people's health."

The National Weather Service's Jacob De Flitch also advises that temperatures will fluctuate, depending on where you are. Communities closer to Puget Sound will likely be cooler than areas farther out.

"The further south you go and away from waters, the hotter it's going to get," De Flitch said. "So right now our forecast for Monday afternoon is looking in the upper 90s. Maybe for North Bend area, near 100, and then kind of Olympia southward, also in the mid to upper 90s."

Check for information about cooling centers in:

King County

Pierce County

Thurston County

Snohomish County

And remember: Do not leave pets or children in cars, check on elderly or vulnerable neighbors, and stay hydrated.

Western Washington air quality

On top of the heat, wildfire smoke could be drifting into the region.

The air quality throughout the Seattle area was good as of Monday morning, but that could change. North-easterly winds began to push smoke from the Sourdough Fire into the Puget Sound region over the weekend. More smoke could be on the way.

"We definitely are seeing some smoke around the region, whether it's more prominent down at the surface or whether it's more of that haze that you see aloft that obscures some of the sky," Cullen said. "We likely will see more of that continuing today."

The haze could diminish visibility in some areas, Cullen added.