Looking at the last 50 years of data and it's pretty clear Seattle is warming up: https://www.currentresults.com/Weather-Decades/USA/WA/Seattl...

Whether this is due to climate change, urban development or something else entirely could certainly be explained in more depth, but the trend is there.

Going back further, you can find 100 degrees in mid July of 1941: https://www.currentresults.com/Yearly-Weather/USA/WA/Seattle...

Though, that was before Sea-Tac was the official weather station: https://www.king5.com/article/news/local/seattle/heres-why-s...

That link is better than the headline because it is averaging hundreds of days for each data point.

A four day heat wave is not very compelling data on its own.

For years you take the train to work every day, at the same time. But you began to notice, that, recently the train has been late a lot. You begin to wonder whether this is due to some change to the train infrastructure.

But behind you someone shouts “the train was 10 minutes late on one day 20 years ago”. Do you dismiss your hypothesis?

Of course not.