Labor Day forecast breaks western WA’s longest heat wave of 2025

The longest stretch of hot weather this year is coming to an end in western Washington. For many, this news is a huge sense of relief.

The Seattle-Tacoma International Airport (SEA) had three straight days hit 90 degrees or better, including Monday’s 91 degrees. Olympia had four straight days in the 90s, topped off with Sunday’s 95 degrees.

Since 2015, SEA has had an average of eight 90-degree or better days in a year. In the latter half of the 20th century, SEA averaged but three days of 90 degrees or hotter. The most was 13 days in 2022, breaking the record of 12 days established in 2015.

The strong high pressure aloft that played a large role in the recent heat wave is holding on, yet weakening a bit. This adjustment is permitting temperatures to ease down a few degrees, back into the upper 70s and 80s for the rest of the week, while many places near shorelines, such as the North Sound region, will drop into the 70s.

Labor Day weekend forecast

Many are looking forward to the Labor Day holiday weekend for one more summer season getaway. Does it always rain, though, on this holiday weekend?

Going back to 2001, SEA has had 13 Labor Day Weekends without any rain at all, including last year. In fact, last year, SEA had highs of 90 and 88 degrees, respectively, on Sunday and Monday of that holiday weekend. The only truly washout of this holiday weekend so far this century was back in 2009 when a total of about 1.20 inches of rain fell.

The weather for this Labor Day weekend looks to be another dry one, yet not nearly as hot as it was last year. The persistent high pressure aloft over the region is expected to gradually weaken the rest of this week and ease inland over the weekend. Yet, it will maintain relatively dry weather with more seasonable temperatures. Average highs in late August are in the mid-70s.

The only fly in the holiday weekend weather will be a threat of thunderstorms over the Cascades. For those venturing into the mountains, be on the lookout for the possibility of thunderstorms in the afternoons and evenings.

High fire danger

Despite the rainfall earlier this month, conditions remain quite dry across the state with moderate to severe drought conditions according to the U.S. Drought Monitor. SEA is more than 6 inches below average for the year thus far; Olympia is greater than 9 inches behind, and usually, wet Forks is nearly 22 inches below average for the year.

The dry conditions mean the threat of wildfires remains high. There are three primary conditions for wildfires—lack of moisture, heat, and an ignition source. Four out of five wildfires are human-caused.

Heading into the holiday weekend, be particularly careful with any burning materials. Avoid tossing cigarettes out of vehicles. There have been many roadside fires this year thus far. If camping, be sure the campfire is cold before leaving the site. An unattended campfire started the Bolt Creek fire near the Stevens Pass Highway in September 2022.

Start of the school year

Selected school districts start the school year this week, but many begin after Labor Day. The weather outlook moving into September continues to offer above-average temperatures to start the school year. No significant rain is in sight either.

Enjoy the gradually cooler weather and have a safe Labor Day holiday weekend, whether at or away from home.

Ted Buehner is the KIRO Newsradio meteorologist. You can read more of Ted’s stories here and follow him on X