Looking at January departures at ORH, the warmest 10 day stretch was Jan 6-15. That averaged +8.9.
Coldest 10 day stretch was Jan 22-31 which averaged -12.3…that stretch actually started with a +8.4 too on Jan 22, but then the next 9 blew that away.
The rest of the days not listed on those two 10-day stretches were slightly BN in the aggregate so you get a total of a -3 month.
December was more impressive on cold departures but January is minimum climo so getting those stretches in January feels a lot colder. December was nearly wire to wire BN cold…only the cutter on 12/18-19 and a couple other random mildish days interrupted the cold departures that month.