John may have written this statement..."and it was winter," simply to remind us of the timing of this event.  However, author A.W. Pink suggests that John was using this word as a literary tool stating that the word had symbolic meaning.  Winter is more than a season, it is a metaphor for cold, dormant and dark.  It reminds me of when Mr. Tumnus said to Lucy, "In Narnia it is always winter, never Christmas."  The hearts of the people of Jerusalem were certainly in a state of "winter."  They were cold, dark & dormant.  Have you ever been in a winter?  What brought you into the Spring?  What brought new life, vibrancy and growth from darkness and "winter"?