According to Environment Canada, the temperature at Toronto's Pearson International Airport did not get above -2 C for the entire afternoon.
It wasn't any warmer in downtown.
"C'est froid," said one man, summing up the sub-zero outdoor temperature just a few days ahead of the official start of spring.
As a result, many of those lining the streets of downtown Toronto were bundled up as they watched waves of Irish dancers, bands and other participants roll by.
But they also came dressed in green and many flamboyant hats, including those emblazoned with sparkles and shamrocks.
Some people were there to enjoy the show and claim Irish roots for the day, while others had a more direct connection to the Emerald Isle.
Mary McAuliffe was wearing a special hat that she had sent over from Dublin so that she could have it for the Toronto parade.
"It's super, it's a lovely day, it's a lovely day to come out and be Irish," said McAuliffe, who is originally from the Irish city of Cork.
The parade caused a number of road closures in the downtown area, many of which lasted through the mid-afternoon.
In advance of the parade, a number of Toronto police officers were sending out tweets urging the public to be responsible when celebrating.
"Have a great day, enjoy the sunshine and use a DD if you’re going to be having any green beers," tweeted Det. Jeff Bangild.
In terms of the cold temperatures on Sunday, it wasn't just a frosty St. Patrick's Day in Toronto.
North of the city in Barrie, Ont., a CBC viewer tweeted a picture of a snowman with green hair and shamrock-shaped eyes.
“It's down-right cold in Barrie this St. Patrick's Day,” George Niemi tweeted to CBC Toronto on Sunday.
It wasn't any warmer down in London, Ont., where police were wary of seeing any repeat of last year's St. Patrick's Day when a riot broke out and dozens of charges were laid.
In the afternoon, London police had been called to just a handful of parties and Const. Ken Steeves said things were "pretty quiet."
But Chief Brad Duncan had warned that police were taking a zero-tolerance approach to unruly parties on St. Patrick’s Day this year.