Average Frost Date Lookup by State
NOAA 1991–2020 Climate Normals — Last spring frost and first fall frost dates with planting windows for major row crops.
Average Frost Dates by State
Corn and soybean planting starts reflect soil temperature targets (50°F and 55°F respectively), typically 1–3 weeks after last spring frost.
| State | Last Spring Frost | First Fall Frost | Frost-Free Days | Corn Plant | Soy Plant | Safe Window Start |
|---|---|---|---|---|---|---|
| ALAlabama | Mar 19 | Nov 14 | 240 | Mar 25 | Apr 15 | Apr 1 |
| ARArkansas | Mar 22 | Nov 10 | 233 | Apr 1 | Apr 15 | Apr 5 |
| CACalifornia | Feb 15 | Dec 1 | 289 | Mar 15 | Apr 1 | Mar 1 |
| COColorado | May 7 | Oct 1 | 147 | May 10 | May 15 | May 15 |
| GAGeorgia | Mar 21 | Nov 13 | 237 | Mar 20 | Apr 15 | Apr 1 |
| IDIdaho | May 15 | Sep 22 | 130 | May 15 | Jun 1 | May 20 |
| ILIllinois | Apr 19 | Oct 19 | 183 | Apr 25 | May 5 | May 1 |
| INIndiana | Apr 22 | Oct 15 | 176 | May 1 | May 10 | May 5 |
| IAIowa | Apr 27 | Oct 7 | 163 | Apr 25 | May 5 | May 5 |
| KSKansas | Apr 13 | Oct 20 | 190 | Apr 15 | May 1 | Apr 20 |
| KYKentucky | Apr 13 | Oct 23 | 193 | Apr 20 | May 1 | Apr 25 |
| MIMichigan | May 10 | Oct 5 | 148 | May 10 | May 15 | May 15 |
| MNMinnesota | May 11 | Sep 28 | 140 | May 5 | May 15 | May 15 |
| MSMississippi | Mar 13 | Nov 19 | 251 | Mar 15 | Apr 10 | Mar 25 |
| MOMissouri | Apr 8 | Oct 25 | 200 | Apr 15 | May 1 | Apr 20 |
| MTMontana | May 20 | Sep 15 | 118 | Jun 1 | Jun 10 | Jun 1 |
| NENebraska | Apr 27 | Oct 7 | 163 | Apr 25 | May 5 | May 5 |
| NCNorth Carolina | Apr 1 | Oct 30 | 212 | Apr 1 | Apr 20 | Apr 10 |
| NDNorth Dakota | May 14 | Sep 22 | 131 | May 15 | May 20 | May 20 |
| OHOhio | Apr 24 | Oct 16 | 175 | May 1 | May 10 | May 5 |
| OKOklahoma | Mar 28 | Nov 7 | 224 | Apr 1 | Apr 20 | Apr 10 |
| OROregon | Apr 15 | Oct 25 | 193 | May 10 | Jun 1 | May 1 |
| PAPennsylvania | Apr 25 | Oct 15 | 173 | May 1 | May 10 | May 5 |
| SDSouth Dakota | May 7 | Sep 29 | 145 | May 5 | May 15 | May 15 |
| TNTennessee | Apr 5 | Oct 28 | 206 | Apr 10 | May 1 | Apr 20 |
| TXTexas | Mar 8 | Nov 20 | 257 | Mar 1 | Apr 1 | Mar 20 |
| VAVirginia | Apr 15 | Oct 22 | 190 | Apr 15 | May 1 | Apr 25 |
| WAWashington | Apr 20 | Oct 15 | 178 | May 10 | Jun 1 | May 1 |
| WIWisconsin | May 5 | Oct 4 | 152 | May 1 | May 10 | May 12 |
Regional Breakdown — Corn Belt States
Frost dates vary significantly within states. Use regional data for more accurate planting decisions.
Illinois
Statewide: Apr 19 → Oct 19
| Region | Last Spring | First Fall | FF Days |
|---|---|---|---|
| Northern IL | May 1 | Oct 8 | 160 |
| Central IL | Apr 15 | Oct 20 | 188 |
| Southern IL | Apr 5 | Nov 1 | 210 |
Indiana
Statewide: Apr 22 → Oct 15
| Region | Last Spring | First Fall | FF Days |
|---|---|---|---|
| Northern IN | May 5 | Oct 8 | 156 |
| Southern IN | Apr 10 | Oct 25 | 198 |
Iowa
Statewide: Apr 27 → Oct 7
| Region | Last Spring | First Fall | FF Days |
|---|---|---|---|
| Northern IA | May 5 | Sep 28 | 146 |
| Central IA | Apr 25 | Oct 8 | 166 |
| Southern IA | Apr 18 | Oct 18 | 183 |
Kansas
Statewide: Apr 13 → Oct 20
| Region | Last Spring | First Fall | FF Days |
|---|---|---|---|
| Western KS | Apr 25 | Oct 10 | 168 |
| Eastern KS | Apr 5 | Oct 28 | 206 |
Minnesota
Statewide: May 11 → Sep 28
| Region | Last Spring | First Fall | FF Days |
|---|---|---|---|
| Southern MN | May 1 | Oct 5 | 157 |
| Northern MN | May 25 | Sep 15 | 113 |
Missouri
Statewide: Apr 8 → Oct 25
| Region | Last Spring | First Fall | FF Days |
|---|---|---|---|
| Northern MO | Apr 20 | Oct 15 | 178 |
| Southern MO (Ozarks) | Apr 1 | Nov 1 | 214 |
Nebraska
Statewide: Apr 27 → Oct 7
| Region | Last Spring | First Fall | FF Days |
|---|---|---|---|
| Western NE (Panhandle) | May 10 | Oct 1 | 144 |
| Eastern NE | Apr 20 | Oct 15 | 178 |
Ohio
Statewide: Apr 24 → Oct 16
| Region | Last Spring | First Fall | FF Days |
|---|---|---|---|
| Northern OH (Lake Erie) | May 5 | Oct 8 | 156 |
| Southern OH | Apr 15 | Oct 25 | 193 |
Frost-Free Days Distribution
States grouped by growing season length. Longer seasons allow more crop options and later planting dates.
Soil Temperature Matters More Than Frost Dates
Frost date tables tell you when it is safe to plant above-ground tissue — but soil temperature is what actually drives germination and biological activity.
- 50°FCorn germination threshold. Plant corn when soil at 2-inch depth is at or above 50°F and trending upward for 3+ consecutive days.
- 55°FSoybean germination threshold. Cold-planted soybeans have higher risk of imbibitional chilling injury. Wait for consistent 55°F+ soil temps.
- 45°F+Biological (AgZyme) application window. Biologicals are most effective applied when soil is at 45°F and rising. Microbial activity accelerates as soil warms through 50–60°F.
Timing Your Biological Application
Frost dates give you the outer bounds of your planting window. Within that window, soil temperature determines optimal biological application timing.
In a typical Corn Belt spring (Iowa, Illinois, Indiana), last spring frost arrives in late April. Soil temps hit 45°F+ around the same time — creating a 2–3 week window for pre-plant biological applications before corn goes in.
Track accumulated growing degree days (GDD) from January 1 to predict when soil temps will cross key thresholds for your specific location.
Plan Your Spring Applications
Use frost dates with soil temperature data to build a week-by-week spring application calendar for biologicals, starter fertilizers, and pre-emerge herbicides.