Sentence:  After heavy rains and an onslaught of mice , snow fell on October 15 , 1825 , and remained on the ground through a <WSD>winter</WSD> so cold that the ice on the Red was five feet thick . 
Meaning of the word marked with <WSD> tags:  the coldest season of the year; in the northern hemisphere it extends from the winter solstice to the vernal equinox