Prior to 1965, October 18 was a very warm day in the US, but after 1965 temperatures plummeted and never recovered.
On this date in 1953, almost the entire US east of the Rocky Mountains was over 80F, and much of the southern US was over 90 degrees.
But if you use Heidi’s cherry pick and start the chart in 1970, you have a steady warming trend. Where would alarmists be without their cherry picks?