Talk to a few Islanders about the weather during the winter and you’ll usually hear that there are certain times of the year like St. Patrick’s Day when a winter storm is more likely.
Let’s look at the frequency of 10+ cm during five day periods from 1944-2016. For the days below we show the percentage of years that had at least 10cm of snow fall on a single day during the 5 day time period focused on that day (that day, 2 days before, and 2 days after).
So on December 17, 10cm+ of snow has fallen in the 2 days before, the day of, and 2 days after on average 57.3% of the time. With this calculation I’m trying to find periods of time that tend to get moderate/heavy snowfall.
December 16, 17 & 18 tend to get a moderate/heavy snowfall the most often followed by the time period of February 15, 16 & 17 and their surrounding days. In a followup post, I will show that the mid-February storms pack a greater punch though. November and March seem to ease us in and out of the winter season when it comes to snow.
It also looks like a heavy snowfall around Boxing Day is more frequent than around St. Patrick’s Day!