Western Washington swelters under hottest temps of the year

After the cool-down last week, temperatures ramped up over the weekend and are forecasted to continue into the middle of the week as higher pressure aloft builds over the Pacific Northwest.

By Wednesday, interior western Washington temperatures may reach the hottest of the year thus far, cracking the 90-degree mark for the second time this year. For the usual warmer places, such as the Cascade foothills and the South Sound region, high temperatures could rise into the mid-90s. Further south toward Portland, the mercury may approach 100 degrees.

Surface thermal low pressure nosing north from the interior valleys of California will reach western Washington Wednesday and help drive the hot temperatures.

Temperatures are not expected to be record-breaking, though. For both the Seattle-Tacoma International Airport (Sea-Tac) and Olympia, the record high temperature on Wednesday is 98 degrees, set in 1979.

Western WA weather: Warm days and nights

July is the warmest month of the year. The expected hot daytime temperatures will also be accompanied by warm overnight readings. Urban areas will likely struggle to have nighttime temperatures cool only into the 60s, while more rural areas will feel some relief, dropping into the 50s.

Cooler conditions during this period of hot weather can be found along the north interior coastline regions and the outer coast, with temperatures forecasted to reach the mid-70s to mid-80s.

Steps to take during hot weather

If unable to travel to cooler locations, here are some steps to stay cool and avoid any heat-related health concerns.

• Seek air-conditioned facilities such as shopping malls and theaters. In the 1990s, only about 15% of homes had air conditioning. Today, that percentage has risen above 40%.
• Stay hydrated by drinking plenty of water and avoid alcoholic beverages.
• During the heat of the day, avoid strenuous activities like running or jogging, and if working outdoors, take breaks and again, drink plenty of water.
• Avoid leaving children and pets in cars, even if for just a few minutes. Temperatures inside a vehicle can soar to well above 100 degrees in less than 10 minutes. So far this year, 13 children have died by being left in hot cars, even with the windows open. Remember – beat the heat, check the back seat!
• The elderly, the very young, and those with heart-related medical conditions are most vulnerable to the stress prolonged heat presents. Check on these family members, friends, or neighbors to help ensure they are doing OK.
• Wear light, loose-fitting clothing to help reflect the heat.
• Area waterways also offer cooling relief. Just remember to wear a properly fitting life jacket. Waters are still cold and falling in results in cold water shock – the leading cause of drownings. There have already been 16 recreational boating fatalities in the state thus far this year.

HeatRisk tool

Be sure to monitor the latest weather forecast and information about this hot weather.

The National Weather Service has a publicly available heat-related resource called HeatRisk. This resource is a color-numeric index that shows a forecast threat of heat-related impacts.

HeatRisk takes into consideration how unusual the heat is for the time of year, the days of the expected hot weather, including not only daytime temperatures, but also temperatures overnight, and the elevated risk of heat-related health impacts.

More 90-degree days these days

In the 20th century, Seattle averaged only three days per year reaching 90 degrees or more. So far this century, that average has risen to five days per year, and in just the last 10 years, the number of days hitting 90 degrees or better is now eight days per year.

Conditions are so dry

The rain deficit across the state continues to grow. Sea-Tac is now over 6 inches of rain behind average for the year thus far, while Olympia is more than 9 inches below average. Usually, wet Forks, on the north coast, is a whopping 20 inches plus below normal for rainfall this year.

Much of the state is now in moderate or severe drought according to the U.S. Drought Monitor. The combination of hot weather and dry conditions means the region is ripe for wildfires.

Wildfire conditions and precautions

There are 11 active wildfires across the state as of Monday morning, including the Toonerville and Bear Gulch Fires in Mason County. The ramp-up in temperatures is going to simply amplify the wildfire potential through at least mid-week.

Some wildfire precautions:

• If camping, be sure the campfire is cold before leaving the site.
• National Parks in the state have campfire bans.
• Many counties and fire districts statewide have outdoor fire bans in place. Check with local authorities to learn the latest details.
• If towing, be sure to tighten tow chains to avoid sparks when dragging on roadways.
• Avoid tossing burning materials such as cigarettes out of vehicles. This behavior is how many roadside fires get started.

A change in the hot weather pattern is expected to begin on Thursday. The thermal surface low pressure is forecast to shift east of the Cascades, permitting onshore flow of cooler air to spread into western Washington – nature’s air conditioning.

This weather pattern change should knock high temperatures back down into the 70s to mid-80s in the interior, and the 60s along the outer coast. Yet, there is no rain in sight to offer any relief from the ongoing dry conditions.

This story was originally published on July 11, 2025. It has been updated and republished since then.

Ted Buehner is the KIRO Newsradio meteorologist. Follow him on X and Bluesky. Read more of his stories here.