Toronto Public Health calls extreme cold weather alerts. Here are the total days and dates for winter seasons going back to 2004-5.

Total days: 1

Dates: Nov 21

Total days: 31

Dates:
Nov 9
Dec 12, 13, 14, 16, 25, 26, 27, 28, 29, 30, 31
Jan 1, 2, 3, 4, 5, 6, 7, 12, 13, 14, 29
Feb 1, 2, 3, 4, 5, 7, 8, 12

Total days: 22

Dates:
Dec 14, 15, 16, 18, 19
Jan 5, 6, 7, 8
Feb 2, 3, 8, 9
Mar 3, 4, 10, 11, 12, 13, 14, 15, 21

Total days: 12

Dates:
Jan 3, 4, 17, 18
Feb 11, 12, 13, 14, 17, 25
Mar 2
Apr 4

Total days: 39

Dates:
Jan 7, 9, 10, 12, 13, 14, 16, 20, 25, 27, 30
Feb 1, 2, 3, 4, 5, 8, 9, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27
Mar 2, 4, 5, 22, 27

Total days: 36

Dates:
Dec 16, 24
Jan 1, 2, 3, 6, 7, 8, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30
Feb 5, 6, 7, 8, 9, 10, 11, 16, 24, 25, 26, 27
Mar 2, 3, 12, 13, 15, 16

Total days: 9

Dates:
Jan 21, 22, 23, 24
Feb 7, 8, 16
Apr 10, 11

Total days: 7

Dates:
Jan 2, 3, 13, 14
Feb 10, 11
Mar 4

Total days: 10

Dates:
Dec 8, 13
Jan 15, 16, 21, 22, 23, 30
Feb 9, 10

Total days: 7

Dates:
Dec 28
Jan 2, 8, 9, 28, 29, 30

Total days: 27

Dates:
Dec 7, 19, 20, 21, 22, 31
Jan 3, 10, 13, 14, 15, 16, 19, 20, 23, 24, 25, 26, 30
Feb 3, 4, 23, 27, 28
Mar 1, 2, 3

Total days: 13

Dates:
Nov 22
Dec 16
Jan 1, 2, 19, 30
Feb 10, 11, 20, 27, 28
Mar 8, 22

Total days: 18

Dates:
Jan 15, 16, 24, 25, 28
Feb 3, 4, 5, 6, 7, 12, 13, 14, 15, 18, 23
Mar 5, 6

Total days: 9

Dates:
Dec 11, 12
Jan 15
Feb 17, 18, 19, 25, 26, 27

Total days: 23

Dates:
Dec 19, 20, 26
Jan 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28
Feb 23, 24, 26
Mar 2, 3, 8, 9, 13