| Years | ≥0˚C AT (˚C·d) | ≥10˚C AT (˚C·d) | ||||
| Zone I | Zone II | Zone III | Zone I | Zone II | Zone III | |
| 1958-2017 | 3514 | 3871 | 4111 | 3076 | 3431 | 3676 |
| 1958-1980 | 3410 | 3764 | 4005 | 2985 | 3340 | 3582 |
| 1981-2000 | 3511 | 3866 | 4108 | 3080 | 3437 | 3686 |
| 2001-2017 | 3620 | 3982 | 4220 | 3162 | 3517 | 3760 |