Ottawa just barely broke a weather record for Sept. 24 on Sunday with a scorching high of 31.8 C and a humidex of 39.
The previous record high temperature was 31.7 C set in 1872, according to weather historian Rolf Campbell.
A heat warning for the region remains in effect.
Sunday also appeared to be the hottest fall day Ottawa has ever seen.
Here's how residents spent the unusually warm autumn day.
Twitter user @snazel got creative and built this makeshift air conditioner to keep cool.
I've set up an improvised AC, with fans blowing through ice. pic.twitter.com/CubRRzRGFU— @snazel
Staying cool indoors with this big nose. pic.twitter.com/EtymEJt1BN— @suzemuse
Air conditioning and fans were popular choices for staying cool.
In my air conditioned house. Screw this weather. I need fall.— @Kat_Fergie
Others, however, didn't seem to mind the late-season heat after a mostly wet July and August.
The unusual warm fall weather continues into the beginning of next week with a high of 32 C and a humidex of 41 on Monday.
Temperatures are set to reach 31 C Tuesday and 28 C Wednesday.
That's when temperatures will return to normal later in the week with highs between 16 C and 17 C.