Winter Severity Indices Rising In Minnesota, Wisconsin

No surprise: Minnesota’s Winter Severity Index through Thursday indicates that, so far, this is shaping up to be a tougher than normal winter for deer. The index adds one point for each day the temperature falls below zero and another point for each day the snow depth is greater than 15 inches. End of season values of fewer than 100 points indicate a mild winter, while values of more than 180 indicate a severe winter.

So far, across Northeastern Minnesota, values range from 50 to 79 in some areas and as much as 100 to 119 in portions of Itasca, Lake and Cook counties.

“At this point in the year the WSI only gives us an indication of the potential for a severe winter,” said Leslie McInenly, big game program leader for the Minnesota Department of Natural Resources. “That said, the index numbers are above the average mid-season levels for much of northern Minnesota but not as high as the severe winters of 1995-96 and 1996-97. In general, I’ve heard from northern area managers that they start seeing increased fawn mortality somewhere between 130-150 (moderate-severe) and adult mortality up around 180.”

WSI maps are found on the DNR’s website,, by clicking the “deer” page under the “hunting and trapping” tab. In past years, area wildlife managers compiled daily information, but now the maps are generated with data from the Minnesota Climatology Working Group.

In Wisconsin, several DNR stations in northwestern counties already have surpassed the “severe” category in WSI readings, according to Kevin Wallenfang, DNR big game ecologist. As a result, Wallenfang anticipates either zero or extremely limited numbers of antlerless deer permits in many northern counties for the 2014 hunting season.

Mike Zeckmeister, district wildlife supervisor in Spooner, said that the first question people usually ask in a hard winter is whether they should start feeding deer.

“It’s always well-intended, but feeding can do more harm than good if done improperly,” Zeckmeister said. “If you choose to feed, please talk to the local DNR wildlife biologist first for advice.”

Wallenfang also offered a reminder that deer feeding is strictly regulated. Feeding is currently limited to a maximum of two gallons per site, must be placed within 50 yards of a dwelling or business building open to the public, and may not be placed within 100 yards of a roadway with a posted speed limit of 45 mph or more.

Wisconsin’s WSI measurements are recorded annually from Dec. 1 through April 30 at 43 stations. One point is accumulated for each day temperatures fall below zero and each day the snow depth is greater than 18 inches.

Winter conditions are considered mild if the station accumulates fewer than 50 points, moderate if between 51 and 80 points, severe if between 81 and100, and very severe if over 100.