Precursor Autumn
Fall often shows harbingers of what the cold season might look like. Over the past thirty years, two cases have stood out: 1989 and 1993. These two winters were particularly cold, while the fall was already cooler than normal.
“In 1989, the rupture was brutal during the fall and November projects us into the heart of winter, explains Réjean Ouimet, meteorologist. Thereafter, Quebec experienced 50 days of cold. December has been the coldest month since the 1940s. Winter will quickly wind down then in January. The fall of 1993 was marked by a snowstorm the day after Halloween. An event heralding the coldest winter ever recorded, a record that still stands. »
Revealing data
For 80 years, the statistics speak for themselves. When the fall is colder than normal, the chances remain high that the winter will follow the same trend. However, note that this result takes into account a recent average temperature, from 1991 to 2020.
“The score is 75% if we refer to the recent normal since 1991, says Réjean Ouimet. Which therefore means that three times out of four, there is a filiation and the winter is also colder than normal when the previous autumn is. »
Quebec is heating up
Quebec is not immune to climate change. The seasons are warmer and the normal evolves in the same way. Considering the average temperature since 1941, the cold autumn and cold winter filiation becomes less frequent. However, this happens almost two out of three times in Montreal.
“This result penalizes the old years when a less hot climate prevailed, considers Réjean Ouimet. We resumed the exercise with a super normal that includes all the data since 1941. “
The big thrill
In Quebec, the data is conclusive. The average is 9 times out of 13 since 1990. The vast majority of cases of abnormally cold autumns show that the winters are also colder.
With the collaboration of Réjean Ouimet, meteorologist.