Judging the impact of winter plays an important role in how many tags the DNR will issue for the year's deer hunt. Since 1975, Wisconsin has kept track of the severity of winter through a formula called the Winter Severity Index, or WSI.
Measurements like snow depth and temperature, are considered mortality factors for deer, and are assigned a point value. "If the minimum temperature gets to zero or below zero, that's one point in the severity index. If the snow depth that day is eighteen inches or higher, on a given day, that's one point."
Winter Severity Index breaks down our winters into four categories, mild, moderate, moderately severe, and very severe. This year's point totals are below 50 points, which puts the severity index at mild. "In years like this where we have what we call a mild winter, where the winter severity is low, we can see up to a thirty percent increase in buck harvest the following fall."