Historical Climate Data

Growing Season Summary
Station: 470045 AFTON, WI

Growing Degree Day Averages
Derived from 1987-2000 Data

Element JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN
GDD
Base 40		 1 8 72 221 580 848 994 932 645 304 62 7 4629
GDD
Base 45		 0 2 37 123 428 698 839 778 497 188 27 3 3584
GDD
Base 50		 0 0 17 60 288 548 684 624 353 106 10 1 2662
GDD
Base 55		 0 0 7 27 172 402 530 470 224 49 3 0 1861
GDD
Base 60		 0 0 2 10 91 264 376 319 124 17 0 0 1189
MGDD*
Base 50		 2 5 50 140 349 548 661 612 402 197 38 4 2981

*Modified Growing Degree Days: Base 50 Ceiling 86.

Growing Season Summary
Derived from 1987-2000 Averages

  Date of Last Spring Occurrence Date of First Fall Occurrence
Base
Temp
°F		 Median Early 90% 10% Late Median Early 90% 10% Late
32 4/29 4/22 4/23 5/18 5/27 10/06 9/21 9/23 10/16 10/22
30 4/22 3/29 4/06 5/18 5/27 10/08 9/23 9/23 10/19 10/22
28 4/14 3/27 4/01 4/30 5/06 10/12 9/23 10/01 10/25 10/27
24 4/08 3/24 3/26 4/18 4/19 11/01 10/13 10/18 11/16 11/15
20 3/30 3/17 3/19 4/09 4/10 11/04 10/19 10/28 12/11 12/21
16 3/16 2/21 2/27 4/06 4/09 11/17 10/29 11/02 12/11 12/22

Length of Growing Season (Days)
Derived from 1987-2000 Averages

Base
Temp
°F		 Median Shortest 10% 90% Longest
32 153 125 135 173 177
30 161 140 142 190 199
28 178 150 160 204 211
24 204 177 189 223 228
20 218 208 209 255 279
16 244 218 221 280 281