Well, it depends where. Canada has a unique climatology for the latest snowfall -- and some of these findings will come as a snowy shock.
The mountains? Even July may feature a little snow at the highest elevations across the province, most recently in 2019 and 2020.
The lower elevations rapidly wind down their snow season by early April -- but occasionally, snowflakes can fly well into the month. Take Nanaimo, which has seen a significant snowfall as late as April 18th, 2008. It's a deeper snowfall than Toronto has ever seen that late! Or take this year, where there's been some accumulating snowfall on Vancouver Island and the Lower Mainland.
We'll come back to you Prairies, but northern Ontario holds on to big dumps of snow into May. Kenora wins this contest, accumulating more than 35 cm on May 11th, 2004.
Southern Ontario, naturally, you're off the hook a little earlier. Through the first couple weeks of April, there's only been a couple of instances of Toronto picking up 10 cm of snow.
Moreover, once you move north into the traditional snowbelts, that risk persists through the month, including in eastern Ontario. Ottawa, you've tacked on five days in late April with more than 10 cm of snowfall -- the most recent being April 16th, 2007.
There's always an exception: The residents of Ottawa lived through history on May 10th, 1963, with more than 15 cm of snowfall. It's a stunning feat, as the average daytime high is 18°C.
And, just because you don't have to shovel it, there have been some recent flake sightings across the Greater Toronto Area (GTA) in May.
May 28th, 2021 became the latest date that Pearson International Airport picked up more than a trace of snow (0.2 cm). An honourable mention is May 11th, 2020, which featured nearly 3 cm of the white stuff.
Naturally, as you work your way up the St. Lawrence Seaway, you're going to encounter May snowfall.
But seriously, what happened on May 10th, 1963?
Montreal picked up more than 21 cm of snowfall in a freak mid-spring storm. As for recent memory -- there hasn't been much May snow this century for Montreal, just more than a trace on May 9th, 2010. Can Montreal reasonably let its guard down? The answer is after April 27th because 2010 featured 30 cm of snowfall on that day.
There have been some significant snows throughout the entire month of April. Remember April 28th, 2020? The Halifax airport picked up 25 cm of snowfall, with similar amounts for the Cape Breton Highlands.
In New Brunswick, even the middle of May can feature some prolific snowfalls, like May 9th, 2020, with 33 cm falling in Woodstock. If you're through the second week of May, you're smooth sailing Atlantic Canada. Unless, that is, you reside in Newfoundland and Labrador -- where there are more than 100 instances of June snowfall across the province.
Nain, Labrador, recorded nearly 30 cm of snowfall on June 9th, 2000, with St. John's even recording a recent June bout of snow -- more than 2 cm worth on June 10th, 2021.
It's time we circle back to the Prairies, and we honestly can't tell you when you could let your guard down – because it can snow even into June in this portion of the country. One particularly noteworthy mid-summer snow was Fort McMurray on Aug. 17th, 1940.
Check this out, featuring some of the biggest Canadian summer snows across the region:
The recent snowfall in Baker Lake is noteworthy, occurring on June 7th, 2018 -- with 20 cm reported.
And the biggest summer snow of all? That title goes to Nain, Labrador, tacking on 36.1 cm of snow on June 1st, 1997.