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 | 2 | 38 | 197 | 532 | 780 | 947 | 871 | 567 | 251 | 39 | 2 | 4229 |
| GDD Base 45 |
0 | 0 | 17 | 111 | 382 | 630 | 792 | 716 | 421 | 145 | 15 | 1 | 3234 |
| GDD Base 50 |
0 | 0 | 7 | 56 | 249 | 480 | 637 | 562 | 284 | 72 | 4 | 0 | 2355 |
| GDD Base 55 |
0 | 0 | 2 | 26 | 145 | 334 | 483 | 408 | 170 | 28 | 1 | 0 | 1599 |
| GDD Base 60 |
0 | 0 | 0 | 11 | 73 | 204 | 330 | 260 | 88 | 8 | 0 | 0 | 979 |
| MGDD* Base 50 |
0 | 2 | 30 | 141 | 336 | 496 | 622 | 564 | 347 | 154 | 25 | 1 | 2721 |
| Date of Last Spring Occurrence | Date of First Fall Occurrence | |||||||||
| Base Temp °F |
Median | Early | 90% | 10% | Late | Median | Early | 90% | 10% | Late |
| 32 | 5/13 | 4/25 | 4/28 | 5/27 | 5/30 | 9/25 | 9/02 | 9/18 | 10/05 | 10/16 |
| 30 | 5/05 | 4/15 | 4/25 | 5/22 | 5/28 | 10/02 | 9/20 | 9/21 | 10/10 | 10/16 |
| 28 | 5/02 | 4/07 | 4/22 | 5/10 | 5/17 | 10/05 | 9/20 | 9/22 | 10/17 | 10/22 |
| 24 | 4/17 | 3/24 | 4/06 | 4/30 | 5/06 | 10/17 | 9/22 | 10/03 | 11/08 | 12/03 |
| 20 | 4/10 | 3/24 | 4/02 | 4/22 | 4/26 | 11/01 | 10/02 | 10/13 | 11/13 | 12/04 |
| 16 | 3/30 | 2/27 | 3/15 | 4/10 | 4/18 | 11/07 | 10/18 | 10/22 | 11/21 | 12/04 |
| Base Temp °F |
Median | Shortest | 10% | 90% | Longest |
| 32 | 137 | 97 | 119 | 151 | 171 |
| 30 | 147 | 118 | 129 | 160 | 171 |
| 28 | 160 | 126 | 139 | 176 | 177 |
| 24 | 184 | 143 | 155 | 213 | 225 |
| 20 | 204 | 161 | 176 | 221 | 233 |
| 16 | 221 | 194 | 203 | 251 | 258 |