We knew early today that the temperature at MSP airport had dropped below zero shortly before midnight on Wednesday. The Twin Cities Office of the National Weather Service investigated the detailed temperature log, and discovered that the initial dip to one below zero occurred at 11:25 PM Wednesday. I spoke with NWS meteorologist Michelle Margraf, who reviewed the MSP data. She confirmed that the temperature stayed at one below zero from 11:25 PM to midnight.
Here is more info from the NWS website,
http://www.crh.noaa.gov/mpx/
The Twin Cities Tied a Record for the Latest Below Zero Temperature
It is official... The Minneapolis/St. Paul International Airport recorded their first below zero temperature shortly before midnight on January 18th. The temperature dropped to -1 at 11:25 PM and stayed at -1 through midnight. Therefore, the record was tied for the latest "below zero temperature" set in 1889 and 2002. The official time of the low was recorded as 11:59 PM, since the official time of the low is the latest time of occurence on a calendar day.
