Thursday, November 14, 2013

Yesterday Was Pretty Darn Cold Historically

Yesterday's 41 degree high was the coldest November 13th since 1977 (38) and, as it turns out, the coldest day to average since January.

While this cold shot, albeit brief, has been mightily impressive by November standards, it didn't quite crack the coldest days to average, ever, department.  Just the fifth coldest day to average since 2010.

Keep in mind that "average" is relative-- and can change based on climate and temperature cycles, plus the increased size of the Philly metro adding a degree or two of warmth as time has progressed.  That said, in a short sample size like a few years you can get an idea of what days tend to stand out as more impressively cold than others.  All data is compared to the current thirty year normal cycle, which reflects data that was collected between 1981 and 2010.

Coldest days to average, using 1981-2010 "normals" for high and low.
The coldest day to average since 2010 was January 24th, 2011 -- high of 25, low of 8, compared to averages of 40 and 25, which yields a day that was 16 degrees below average. January 23rd of this year comes in very close to that with a temperature of 22 and 12 for a departure of 16 from normal.

Another point I want to make as well -- the temperatures themselves aren't all necessarily the coldest ever -- yesterday was the third coldest (tied with 1996) for this particular date. October 29th, 2011 (Anniversary of Snowtober) was the coldest high for that date on record, with the other dates safely above the cold thresholds of those particular days.