Growing Degree Day Averages
Derived from 1971-2000 Data
| Element | JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP | OCT | NOV | DEC | ANN |
| GDD Base 40 |
0 | 1 | 37 | 211 | 564 | 810 | 981 | 906 | 588 | 260 | 37 | 2 | 4402 |
| GDD Base 45 |
0 | 0 | 16 | 121 | 413 | 660 | 826 | 751 | 441 | 152 | 14 | 0 | 3400 |
| GDD Base 50 |
0 | 0 | 6 | 62 | 276 | 511 | 671 | 596 | 302 | 76 | 4 | 0 | 2509 |
| GDD Base 55 |
0 | 0 | 1 | 29 | 164 | 364 | 516 | 441 | 185 | 31 | 1 | 0 | 1736 |
| GDD Base 60 |
0 | 0 | 0 | 11 | 85 | 229 | 363 | 291 | 98 | 10 | 0 | 0 | 1090 |
| MGDD* Base 50 |
0 | 1 | 27 | 142 | 347 | 517 | 650 | 590 | 355 | 154 | 22 | 1 | 2811 |
| Date of Last Spring Occurrence | Date of First Fall Occurrence | |||||||||
| Base Temp °F |
Median | Early | 90% | 10% | Late | Median | Early | 90% | 10% | Late |
| 32 | 5/06 | 4/08 | 4/25 | 5/21 | 5/27 | 9/28 | 9/03 | 9/21 | 10/10 | 10/16 |
| 30 | 5/02 | 4/06 | 4/11 | 5/15 | 5/27 | 10/03 | 9/20 | 9/22 | 10/15 | 10/21 |
| 28 | 4/28 | 3/29 | 4/08 | 5/09 | 5/14 | 10/07 | 9/20 | 9/24 | 10/19 | 10/22 |
| 24 | 4/13 | 3/24 | 4/03 | 4/26 | 5/06 | 10/24 | 10/02 | 10/04 | 11/04 | 11/11 |
| 20 | 4/08 | 3/23 | 3/26 | 4/16 | 4/22 | 11/01 | 10/02 | 10/16 | 11/13 | 11/15 |
| 16 | 3/31 | 2/26 | 3/15 | 4/09 | 4/16 | 11/12 | 10/19 | 10/29 | 11/28 | 12/05 |
| Base Temp °F |
Median | Shortest | 10% | 90% | Longest |
| 32 | 146 | 113 | 127 | 161 | 179 |
| 30 | 158 | 128 | 138 | 176 | 188 |
| 28 | 163 | 139 | 142 | 178 | 188 |
| 24 | 192 | 151 | 170 | 210 | 225 |
| 20 | 207 | 177 | 190 | 219 | 233 |
| 16 | 227 | 193 | 210 | 250 | 260 |