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!
| Date (and 2 days before and after) | Percent frequency of 10+ cm of snow |
| December 17 | 57.3 |
| December 16 | 54.7 |
| February 17 | 48.2 |
| December 18 | 45.8 |
| February 15 | 44.1 |
| February 16 | 44.1 |
| December 26 | 43.3 |
| January 05 | 43 |
| January 06 | 42.9 |
| February 14 | 42.7 |
| December 15 | 42.2 |
| January 31 | 41.7 |
| January 03 | 41.4 |
| December 19 | 40.3 |
| January 04 | 40.1 |
| December 14 | 39.4 |
| December 25 | 39.2 |
| December 20 | 39.1 |
| February 02 | 39.1 |
| February 01 | 39 |
| January 02 | 38.8 |
| February 07 | 38.7 |
| February 18 | 38.7 |
| January 18 | 38.7 |
| January 16 | 38.6 |
| January 15 | 38.3 |
| February 03 | 37.5 |
| January 29 | 37.4 |
| February 06 | 37.3 |
| February 13 | 37.2 |
| February 25 | 37 |
| January 14 | 36.9 |
| March 02 | 36.8 |
| December 24 | 36.6 |
| December 27 | 36.2 |
| February 04 | 36.2 |
| January 30 | 36.1 |
| January 17 | 36 |
| January 19 | 36 |
| February 08 | 35.9 |
| February 10 | 35.9 |
| January 07 | 35.9 |
| March 03 | 35.6 |
| March 01 | 35.4 |
| February 05 | 34.7 |
| February 24 | 34.3 |
| February 26 | 34.3 |
| January 12 | 34.2 |
| December 23 | 33.8 |
| December 28 | 33.4 |
| February 11 | 33.3 |
| February 19 | 33.3 |
| January 08 | 33.2 |
| January 09 | 33.2 |
| February 09 | 33 |
| January 13 | 32.8 |
| February 27 | 32.7 |
| February 28 | 32.7 |
| February 29 | 32.7 |
| December 04 | 32.3 |
| December 05 | 32.3 |
| December 02 | 32 |
| December 29 | 32 |
| January 01 | 31.9 |
| January 20 | 31.9 |
| March 16 | 31.8 |
| December 03 | 30.7 |
| December 01 | 30.6 |
| February 12 | 30.4 |
| March 14 | 30.4 |
| February 23 | 30.3 |
| January 28 | 30.2 |
| January 10 | 30.1 |
| January 11 | 30.1 |
| December 13 | 29.7 |
| December 22 | 29.6 |
| January 21 | 29 |
| March 15 | 29 |
| March 17 | 28.9 |
| March 04 | 28.8 |
| December 06 | 28.1 |
| December 31 | 27.8 |
| December 30 | 27.7 |
| December 07 | 26.7 |
| December 08 | 26.7 |
| December 21 | 26.6 |
| November 30 | 26.4 |
| February 21 | 26.2 |
| January 22 | 26.2 |
| March 05 | 26.2 |
| January 27 | 26.1 |
| March 13 | 25 |
| February 22 | 24.9 |
| March 06 | 24.9 |
| March 18 | 24.8 |
| February 20 | 23.6 |
| November 29 | 23.6 |
| January 25 | 23.5 |
| April 09 | 23.2 |
| March 07 | 22.1 |
| January 26 | 22 |
| April 08 | 21.8 |
| December 12 | 21 |
| March 12 | 20.9 |
| January 23 | 20.8 |
| March 08 | 20.8 |
| March 09 | 20.8 |
| April 01 | 20.7 |
| March 10 | 20.7 |
| April 02 | 20.6 |
| March 24 | 20.6 |
| April 10 | 20.5 |
| December 10 | 19.5 |
| December 11 | 19.5 |
| November 28 | 19.5 |
| March 19 | 19.3 |
| March 20 | 19.3 |
| March 21 | 19.2 |
| March 23 | 19.2 |
| March 25 | 19.2 |
| April 07 | 19.1 |
| December 09 | 18.2 |
| January 24 | 18 |
| March 30 | 17.9 |
| April 03 | 17.8 |
| March 22 | 17.8 |
| April 05 | 17.7 |
| April 06 | 17.7 |
| March 11 | 16.6 |
| March 31 | 16.6 |
| March 29 | 16.5 |
| March 26 | 16.4 |
| March 27 | 15.1 |
| March 28 | 15.1 |
| April 11 | 15 |
| November 16 | 14 |
| April 04 | 13.7 |
| April 30 | 13.7 |
| April 27 | 13.6 |
| April 28 | 13.6 |
| November 17 | 12.6 |
| November 18 | 12.6 |
| November 27 | 12.6 |
| April 29 | 12.3 |
| November 15 | 11.2 |
| November 19 | 11.2 |
| November 20 | 11.2 |
| April 12 | 10.9 |
| November 14 | 9.8 |
| November 21 | 9.8 |
| November 22 | 9.8 |
| November 26 | 9.8 |
| April 21 | 9.6 |
| April 26 | 9.5 |
| November 25 | 8.4 |
| May 01 | 8.3 |
| April 20 | 8.2 |
| April 22 | 8.2 |
| April 23 | 8.2 |
| April 24 | 8.2 |
| November 23 | 7 |
| November 24 | 7 |
| November 12 | 5.6 |
| November 13 | 5.6 |
| April 13 | 5.5 |
| April 14 | 5.5 |
| April 19 | 5.5 |
| April 25 | 5.5 |
| April 18 | 4.2 |
| May 02 | 4.2 |
| November 08 | 4.2 |
| November 09 | 4.2 |
| November 10 | 4.2 |
| May 04 | 4.1 |
| May 05 | 4.1 |
| May 06 | 4.1 |
| May 07 | 4.1 |
| May 08 | 4.1 |
| April 15 | 2.8 |
| April 16 | 2.8 |
| April 17 | 2.8 |
| May 03 | 2.8 |
| November 11 | 2.8 |
| May 09 | 1.4 |
| November 06 | 1.4 |
| November 07 | 1.4 |
| October18 | 1.4 |
| October19 | 1.4 |
| October20 | 1.4 |
| October21 | 1.4 |
| October22 | 1.4 |