Hamilton County, Iowa / Corn
Total GDD:
2961
(Oct 15)
Day 167 / 168 (99%)
Current Season
Total GDD:
2961
(Oct 15)
Method: 50°F | 86°F max
7-Day Daily Avg: 9.4
7-Day Projection: 3027 by Oct 22
Season: May 01, 25 - Oct 15, 2025
Key Freeze Dates (32°F)
Last Freeze:
10%: 04-19
50%: 05-05
90%: 05-15
10%: 04-19
50%: 05-05
90%: 05-15
First Freeze:
10%: 09-19
50%: 10-02
90%: 10-16
10%: 09-19
50%: 10-02
90%: 10-16
Growing Degree Days (GDD) track heat accumulation to predict when plants reach growth stages, pests emerge, and diseases become active.
Thresholds mark specific GDD values when events typically occur, with crossing dates showing when your season reaches each milestone.
Thresholds & Notes
VE - Emergence
120
°D
May 12, 2025
|
May 13, 2024
|
May 12, 2023
|
May 13, 2022
Growth Stage
Coleoptile breaks surface
V2 - Two Leaf
200
°D
May 16, 2025
|
May 19, 2024
|
May 18, 2023
|
May 18, 2022
Growth Stage
Two collared leaves
V6 - Six Leaf
475
°D
Jun 11, 2025
|
Jun 7, 2024
|
Jun 3, 2023
|
Jun 9, 2022
Growth Stage
Growing point above ground, nodal roots active
V10 - Ten Leaf
815
°D
Jun 25, 2025
|
Jun 24, 2024
|
Jun 22, 2023
|
Jun 24, 2022
Growth Stage
Ear shoots developing
V14 - Fourteen Leaf
1135
°D
Jul 8, 2025
|
Jul 11, 2024
|
Jul 8, 2023
|
Jul 8, 2022
Growth Stage
Tassel forming, ear size determined
VT - Tasseling
1350
°D
Jul 18, 2025
|
Jul 21, 2024
|
Jul 20, 2023
|
Jul 17, 2022
Growth Stage
Tassel fully emerged, pollen shed begins
R1 - Silking
1450
°D
Jul 23, 2025
|
Jul 26, 2024
|
Jul 25, 2023
|
Jul 21, 2022
Growth Stage
Silks visible, pollination critical
R3 - Milk Stage
1925
°D
Aug 13, 2025
|
Aug 19, 2024
|
Aug 16, 2023
|
Aug 13, 2022
Growth Stage
Kernels yellow, milky fluid
R5 - Dent Stage
2450
°D
Sep 13, 2025
|
Sep 18, 2024
|
Sep 10, 2023
|
Sep 9, 2022
Growth Stage
Dent forming, 55% moisture
R6 - Black Layer
2700
°D
Sep 27, 2025
|
Oct 3, 2024
|
Sep 28, 2023
|
Sep 26, 2022
Growth Stage
Physiological maturity, 30-35% moisture