Simcoe County has four distinct seasons: winter, spring, summer and autumn (or fall). Each season has its own type of weather. The following table shows the average temperature for each season; however, temperatures can vary.
Winter | December | 0.0 | -7.9 | 62 | 21 |
| January | -3.2 | -12.8 | 80 | 15 |
| February | -2.0 | -12.1 | 39 | 13 |
Spring | March | 3.2 | -7.5 | 28 | 29 |
| April | 10.6 | 0.0 | 5 | 58 |
| May | 18.1 | 6.5 | 0 | 77 |
Summer | June | 23.4 | 12.0 | 0 | 87 |
| July | 26.0 | 15.0 | 0 | 73 |
| August | 24.8 | 14.2 | 0 | 93 |
Fall | September | 20.1 | 9.6 | 0 | 98 |
| October | 13.2 | 3.7 | 3 | 74 |
| November | 6.1 | -1.4 | 21 | 62 |