Seafair week forecast shows comfortable temps as July 29 marks anniversary of Seattle’s old heat record

Nearly everyone who was in the Pacific Northwest in June 2021 remembers the historic “heat dome.” At Seattle-Tacoma International Airport (SEA), the thermometer soared to 108 degrees on June 28, crushing the previous all-time hottest record of 103 degrees.

Olympia hit 110 degrees that day, and Bellingham and Everett both peaked at 100 degrees. Meanwhile, Portland, Oregon, climbed to 116 degrees, and in eastern Washington, Hanford just outside of the Tri-Cities reached 120 degrees. Even Hoquiam along the central coast hit 103 degrees. That “heat dome” event was clearly historic.

Before the June 2021 heat dome and its record-crushing hot temperatures, the previous all-time record high temperature at SEA was 103 degrees. That hot temperature happened on July 29, 2009. Wednesday the 29 will mark 18 years since the hot day.

Before the 103 degrees set on that date, the record at SEA was 100 degrees, established on July 20, 1994.

One of the historic, driest dates

July 29 also happens to be one of the driest dates in Seattle history. Referencing weather records dating back into the 1890s, measurable rain fell on this date only six times at the old Federal Building weather station and just five times at SEA, most recently in 2024. Measurable rain is defined as one one-hundredth of an inch or more.

This month is again drier than average. At SEA, only 41 hundredths of an inch has fallen, leaving a rain deficit of over 2 inches so far this year. Weather forecast charts do not offer much in the way of meaningful rain for the rest of the month.

Seafair week

This is Seafair week. The Blue Angels and other air show participants arrive early this week, make practice runs Thursday and Friday, and perform during the weekend. The hydros also arrive early this week from the Tri-Cities and make their preparations on Lake Washington during the week before racing over the weekend.

Seasonable warm weather with high temperatures mainly in the 70s to lower 80s will greet the hydros, air show participants, and fleet week vessels along the Seattle waterfront. Low-level onshore airflow from the Pacific Ocean is expected to keep temperatures far more moderate than the hot temperatures not only east of the Cascades, but also across much of the nation.

The onshore flow will also keep wildfire smoke from all the wildfires in British Columbia and eastern Oregon and Washington from making its way into western Washington this week. This weather pattern should keep air quality in good shape through Seafair weekend.

The Seattle Mariners also return home from their current road trip to take on the Minnesota Twins for a three-game weekend series starting Friday.

Weather conditions for Seafair, the Mariners’ home series, and any other outdoor events in the region should feel comfortable.

Given the dry conditions, though, everyone needs to be very careful with any burning materials to avoid any fires starting.

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