| Classification | Season | Period | |
| WTR | winter | From the winter solstice to the day before the spring equinox | 12/22-3/20 |
| SPR | spring | From the spring equinox to the day before the summer solstice | 3/21-6/20 |
| SMR | summer | From the summer solstice to the day before the autumn equinox | 6/21-9/22 |
| AUT | autumn | From the autumn equinox to the day before the winter solstice | 9/23-12/21 |