The white dots on the graph above show the HLA (high-low average) for each month since January 2010, while the green lines show the trend for October.
(Copyright © 2017 by Wil C. Fry. Some rights reserved.)
Note: This is not the “coolest on record”; just the coolest of the past eight Octobers. I don’t know when the coolest one was; many of the daily records come from the 1980s and ’90s. Also note: The previous three Octobers (2014-16) were each in succession the warmest in recorded history for this area. The drop in 2017 simply returned us to the previous level.
Only four days hit 90°F or higher, which is among the fewest for the past eight Octobers. If we don’t hit 90°F again this year, then we had a fairly early end to the 90-degree days, but 2017 still saw the longest-ever span from first 90-degree day to the last one, at 234 days, from Feb. 23 to Oct. 14.
94°F was the high for the month, which is close to average for the past eight years (and one of the rare years in which October’s high beat May’s high).
38°F was our low, which is cooler than the recent average. This follows three years of outstandingly warm lows for October.
Two daily record highs were set in October 2017 — Oct. 8 and 9 — but no record lows.
We received 2.14 inches of rainfall in October, the third-wettest October in recent years (but the third-driest month in 2017).
Five days saw precipitation, which is exactly average for October.
Earlier this year, due to the surprising warmth, I began to suspect 2017 would surpass 2012 as our hottest year of all time. This has become increasingly less likely, with three consecutive months (August-October) going cool. We will need a surprisingly warm November and December to finish the coup.
(But note that August-October were not terribly warm in 2012 either. The record came from the winter and spring months.)
Four of 2012’s monthly HLA records still stand (January, April, May, and December).
Rainwise, we have already received more rain than four entire years (2011 and 2014), and if current trends continue we’ll likely tie 2016 for second place (2015 still being the wettest recent year). More than any of the past seven years, 2017 has seen the rain spread evenly throughout most months, with few long dry spells.