Unseasonably Mild and Wet December Across North Central and Northeast Wisconsin

December 2015 will go down in the record books as the warmest and wettest December on record across North Central and Northeast Wisconsin. It may also be remembered for how impressively these records were broken, with most record marks being eclipsed easily.

Green Bay

At Green Bay, the average temperature for the month was 34.5 degrees, and was the warmest December on record. Green Bay warmed to 55 degrees on the 13th and 14th. Green Bay set or tied record highs on the 10th (54 degrees), the 13th (55 degrees), 14th (55 degrees), and the 23rd (52 degrees).  Green Bay reached 50 degrees five times during the month, one short of the record of 6 days set in 1998. Record high minimum temperatures were also established on the 10th (40 degrees), the 14th (tied at 37), and the 23rd (38 degrees). There were zero days of subzero temperatures during the month, the last time this occurred was in 2012.

December 2015 will go down in the record books as the wettest December on record, clearing the old record of 4.20 inches set in 1893 by the same amount that falls in an average December.  The two day rainfall total of 3.51 inches on the 13-14th broke the previous two day precipitation total of 2.50 inches set on December 14-15th set in 1891. The combination of the unseasonably mild and wet weather allowed for green grass in the Green Bay and Appleton areas. The heaviest rains caused urban street flooding, while several rivers went above flood stage. 

Surprisingly, the majority of the precipitation this month fell as rain, a feat quite uncommon in December. Nowhere was this more stark than in Green Bay, which had received only a trace of snowfall the entire month until December 26. Indeed, Green Bay's precipitation record had fallen on the strength of the rainfall alone. The powerful winter storm of December 28-29 simply provided an impressive amount of padding to the new record, but also took the city from no measureable snowfall to the monthly average in one event!

 Rhinelander

At Rhinelander, the average temperature for the month was 29.0 degrees, and was the warmest December on record.  Rhinelander warmed to 49 degrees on the 10th, which set a new record high for the date. Several record high minimum temperatures were set during the month, including: the 8th (34 degrees), the 10th (36 degrees), the 11th (33 degrees) and the 13th (35 degrees). There were no days below zero during the month. The last time there were zero days of subzero temperatures in December occurred in 1959. Like Green Bay, Rhinelander also demolished its precipitation record. Though its snowfall was a bit more evenly distributed, the amount of rain resulted in a lower snowfall total than one might expect. For instance, the old record December in 1968 saw 46" of snow with its liquid equivalent of 2.74". In contrast, Rhinelander only reached 12.7" of snow on 3.96" of liquid equivalent precipitation.

 Wausau

At Wausau, the average temperature for the month was 31.4 degrees, and was the warmest December on record.  Wausau warmed to 51 on the 10th, which set a new record high for the date. A record high was also set on the 23rd (44 degrees). Several record high minimum temperatures were set during the month, including: the 10th (39 degrees), the 11th (34 degrees), and the 13th (38 degrees). There were zero days of subzero temperatures during the month, the last time this occurred was in 2012. Not to be outdone by Green Bay and Rhinelander, Wausau also had a month where precipitation soared far beyond the old record.