Sea-Tac Airport hit 89 degrees on Sunday, and Seattle got a new Flag Day heat record in the process. The old mark was 86. Now the region is staring at one more very hot day before marine air starts to bring real relief.
That is why Seattle weather is drawing so much attention today. A heat advisory remains in effect for most of the region through Tuesday, and it does not ease overnight the way people might hope. At 3 a.m. early Monday, temperatures were still in the 70s in some Seattle neighborhoods, while lows around Puget Sound were expected to take much of the night to slip into the 60s. Forecasters called it tough sleeping weather for homes without air conditioning.
Monday may still add to the heat before the cooldown arrives. Seattle is expected to be near 90 degrees, and could reach 90 if enough sunshine breaks through increasing cloud cover. The city is also likely to tie or beat the existing record high for the 15th, 88 degrees, which is the kind of number that makes a two-day stretch feel like a summer arrival before Summer has even officially begun. One more day of low 90s is expected around the South Sound, with Issaquah, Maple Valley, Puyallup, Auburn, Lakewood, Tacoma, Olympia, Centralia, Shelton and Elma all forecast to hit 90 on Monday. Wenatchee and Omak are expected to climb into the upper 90s.
That is the part that does not quite match the simple headline of heat followed by relief. Monday could still tie or beat a record high while the advisory is still in place, even as the pattern is already shifting underneath it. The marine push is expected to reach Puget Sound on Tuesday, but not before the region gets another day of warmth that lingers into the night. Sea-Tac Airport already showed how far temperatures can jump in this setup, and the next step is not an abrupt break but a slow turn.
Forecasters said a low-pressure system sliding in from Canada toward Montana will shift the pressure gradient and drive onshore flow, helping cooler marine air move inland. The heat advisory is set to expire at 5 a.m. Tuesday, and the broader cooldown is expected that day as the marine push reaches Puget Sound. After that, temperatures are expected to settle mainly into the 70s for the rest of the week, with a few days able to climb back to 80, including Friday and Sunday. The region may even pull down some mist or drizzle by Wednesday morning.
The coast will cool too. Stratus and fog are expected to return to ocean beaches late Monday, and temperatures at La Push and Long Beach are expected to drop into the 60s Monday after soaring into the 80s over the weekend. Even Monday's Belgium vs. Egypt match will feel the heat, with about 85 degrees expected at kickoff and near 90 by the end. For people waiting for Seattle weather to break, Tuesday is the first real answer.
