Mr. Gottschalck said temperatures in that large section of the country have averaged between six and eight degrees above normal so far this month — a jump from September, which was also warmer than usual.
The culprit? Warm southwesterly winds shifted northward by high pressure patterns in the Northeast and low pressure in the Southwest, according to Mr. Gottschalck’s analysis.
He said that temperatures running so much higher than average for three weeks in October was unusual. “It’s a pretty strong anomaly.”
Discerning the root cause of any particular weather pattern in real time is not possible with current technology, and Mr. Gottschalck cautioned against attributing the balmy atmosphere to a new norm connected with climate change.
It could take several decades of research to know definitively why it’s still too hot to try that new soup recipe, he said.
But, he added, long-term trends are clear. Over the decades, “there is definitely what we would call a secular warming trend, with above-average temperatures occurring across much of the country.”
Last year, October was similarly hot, and across an even broader swath of the continental United States.
For anyone who can’t stand the heat, change may be just around the corner. As soon as this weekend, Mr. Gottschalck said, temperatures in the affected regions are expected to drop closer to seasonal averages. That will mean fewer 70-degree days and more 50-degree ones.
Plan your Halloween costume accordingly.