The much dreaded and sensationalized Polar Vortex will drop over Ontario this weekend for the first time since 2015. Usually, this arctic air remains near the pole, but this weekend this area of extremely cold air will split into three parts and move south. It will not only bring frigid conditions this weekend but could set up a pattern where periods of very cold air persist over the next month.
The cold air arrives through the day on Friday with temperatures starting near -7°C in the morning and falling to near -15°C by sunset. Windchill values will fall below -20°C around noon and keep dropping as well. Overnight lows should dip to near -30°C.
On Saturday we will see a mix of sun and cloud with frigid cold remaining in place. Daytime highs will be near -17°C and then overnight lows fall to at least -30°C, likely lower in outlying areas.
Sunday will be sunny but remain very cold as daytime highs will only climb to near -20°C. North winds will bring windchill values between -30°C and -40°C. Skies will be mainly sunny with the chance of the odd flurry.
Monday will start to warm up, but temperatures will remain below normal values for late January.