It feels like June. It’s the end of September though. A month that was hotter and drier than seasonal norms, summarizes Environment Canada. In the parks and rivers of the metropolis, on this last day of September, the sun brings joy to young and old alike.
“It’s truly a gift, today and even all week,” rejoices François, returning from a trip to Mount Royal with his partner, Jean.
PHOTO JOSIE DESMARAIS, THE PRESS
François and Jean, met at Jeanne-Mance Park
Around him, people stroll in Jeanne-Mance Park. Some are basking in the sun, in swimsuits. Guitar tunes resonate. The smell of barbecue sneaks in. The sun floods the flowerbed through the leaves of the trees which are just beginning to color. On the Lachine Canal, passers-by on paddle boards rub shoulders with families fishing.
The mercury reached a comfortable level of 23°C on Saturday in Montreal. In the coming days, with the arrival of October, it should touch 26°C, before falling again towards the end of the week.
This month of September was on average 2 to 3 degrees warmer than seasonal norms, explains Dominic Martel, meteorologist for Environment Canada. This difference was particularly marked in Montreal, with 18.5°C on average, compared to 15.5°C in seasonal norms.
All of Quebec experienced a similar scenario, specifies the meteorologist. In Trois-Rivières, where the normal is 14°C, we observed 16.3°C. On the Quebec side, the mercury was on average at 16.2°C, compared to 12.7°C usually. In Saguenay, the normal is 12°C, we observed 15.4°C. In Mont-Joli, the average was 15°C, compared to the usual 12°C. And 14.6°C in Gaspé, compared to 11.5°C in normal times.
Not to mention that in the majority of sectors of Quebec, with the exception of the East, precipitation was below normal. This is particularly obvious in Montreal, where only 27 mm of rain were recorded, compared to 83 mm usually in September. A 68% rain deficit.
“We must remain vigilant”
This sequence of good weather should not make us lose sight of the risks linked to climate change, believes Philippe Gachon, professor of hydroclimatology in the geography department of the University of Quebec in Montreal (UQAM).
“We have just experienced the hottest summer ever recorded in Canada,” he recalls. Particularly in the North, there is a risk of ending the month of September with three or even four consecutive months of warmer temperatures. [que les normales]. It’s unheard of, it’s exceptional. And this is a bit like what is happening across the globe. »
Indeed, Agence France-Presse reported on Friday that the month of September 2023 was the hottest ever recorded in France, Germany, Poland or Switzerland.
However, periods of intense precipitation, followed by droughts, are among the anticipated effects of climate change, recalls Mr. Gachon.
“Right now, the North Atlantic continues to be much warmer than usual,” he notes. This means more humidity and low pressure systems that move more slowly than usual. » Result: storms that stay in the same place with more precipitation, suddenly.
Like the rain that fell on New York on Friday, flooding the streets and paralyzing part of the subway system, illustrates the professor.
Despite everything, it is worth celebrating the dry weather this fall in Quebec: the rainy summer had raised the level of lakes and rivers and saturated the soil. “The month of September allowed everything to dry out a little,” recognizes Mr. Gachon. And that limited the risk of flooding. » Nevertheless, according to him, autumn is barely beginning. “We must remain vigilant. »
Effects on fall foliage?
A warmer and drier autumn can, in certain cases, delay the appearance of autumn colors, also affirms Michel Labrecque, head of the research division at the Botanical Garden.
Although it is mainly the shortening of periods of sunshine that influences the cessation of photosynthesis production in trees, temperature can also play a role.
“If it’s very hot, it can slow down the process and it can cause the fall colors to appear later,” explains the researcher. “What we are seeing this year, especially in southern Quebec, is a little less advance in the fall colors than we would normally see. »
According to Bonjour Québec’s interactive map which allows you to follow fall colors, the majority of regions bordering the St. Lawrence River are only at the beginning of the process, as of September 28. The color season lasts from September 15 to October 15.
Drought can also cause leaves to fall before they change color, adds Mr. Labrecque. “Fortunately, we had a very, very wet summer,” he says. We are not in a catastrophic situation. We can all enjoy the good weather and the spectacle of colors. »