On the morning of October 23rd at 4:45 am the temperature went below zero for the first time since the spring. It stayed below zero for almost 4 hours with the lowest temperature being -0.9°C.
The bigger news is that by my calculations the frost free season went from May 1st to October 22nd this year which is a total of 175 days. This is the longest frost free season I have been able to find since records began in the region in 1915. This year just beat out 1941 when they had a stretch of 174 days above zero.
For full disclosure I just want to mention that there isn't enough data for 1937 and 1938 to be included in the analysis.