We know winter brings the cold, but when does southern Ontario typically see the coldest days of the entire year?
According to climate data, the period between January 15th and 21st is typically when the region experiences its chilliest week, with cities like Toronto, Hamilton, and Ottawa seeing their lowest average temperatures during this time.
Evergreen: Southern Ontario’s coldest time of year is mid to January
On average, Toronto hits highs of -2°C and lows dipping to -11 during that timeframe.
EVERGREEN: Toronto Pearson average temperatures during winter
Why does it get so cold mid to late January?
Even though the shortest day of the year occurs in late December, we experience a delayed cold due to what’s known as seasonal lag. What that means is that the land and large bodies of water, like the Great Lakes, retain heat from the warmer months and release it gradually, which delays the full onset of winter’s chill.
At the same time, shorter daylight hours let more heat escape overnight than is gained during the day, stretching out the cold.
Also, by mid to late January, Arctic air masses become more settled, pushing colder temperatures further south and intensifying the chill.
So when we hit the coldest days, get ready to bundle up—whether it’s the usual winter chill or even a surprise above-average spell.
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