[squidfood]

On the Pacific NW coast where this is happening, cool marine air will push in and eventually overwhelm the system holding in the heat. The change can be quite abrupt, as the two systems wrestle for dominance, I've felt it (in Seattle) is as a sudden breeze followed by what feels like turning the AC on - literally a 5-10deg temp drop in minutes and can drop 30deg in a couple hours. It doesn't generally end with full-on rain but with cool coastal clouds rolling in.

[throwawaysea]

In this case it was a 40-50 degree (Fahrenheit) swing from the record high to the overnight lows as the air compression from sinking air off the mountains dispersed and marine air came onshore: https://cliffmass.blogspot.com/2021/06/even-more-extreme-ext...