The climatologically coldest week of the year follows the shortest day of the year by about a month. This is the coldest week of the year. The coldest record lows ever recorded were in this week, including -25 in Cincinnati in 1977. We have already gained daylight in the weeks since the shortest day of the year. We have another 6 weeks of climatological winter. Climatological spring begins March 1 when the average day length equals mid-October and the average temperature equals December 1.