Iowa frost dates
Across 148 weather stations in Iowa, the median last spring frost runs from Apr 10 in Keokuk Lock Dam to May 8 in Elkader, and the first fall frost from Sep 28 to Oct 27.
Iowa at a glance
- Weather stations
- 148
- Earliest last frost
- Apr 10 Keokuk Lock Dam
- Latest last frost
- May 8 Elkader
- Longest season
- 198 days Keokuk Lock Dam
- Typical season
- about 164 frost-free days
- Hardiness zones
- Zones 4b to 6a
Frost dates by weather station
| Weather station | Last spring frost | First fall frost | Frost-free days | Zone |
|---|---|---|---|---|
| Albia | Apr 24 | Oct 16 | 173 | 5b |
| Algona | Apr 30 | Oct 6 | 160 | 5a |
| Allerton | Apr 21 | Oct 19 | 178 | 5b |
| Allison | Apr 27 | Oct 8 | 165 | 5a |
| Ames 5 mi SE | Apr 26 | Oct 12 | 168 | 5b |
| Ames 8 mi WSW | Apr 23 | Oct 14 | 173 | 5a |
| Ames Municipal Airport | Apr 26 | Oct 8 | 164 | 5b |
| Anamosa 1 mi WNW | May 1 | Oct 4 | 154 | 5a |
| Anamosa 3 mi SSW | Apr 27 | Oct 13 | 170 | 5a |
| Ankeny | Apr 23 | Oct 15 | 173 | 5b |
| Atlantic | Apr 30 | Oct 2 | 153 | 5a |
| Audubon | May 2 | Oct 3 | 154 | 5a |
| Battle Creek | May 1 | Oct 1 | 153 | 5a |
| Beaconsfield | Apr 23 | Oct 17 | 176 | 5b |
| Bedford | Apr 24 | Oct 15 | 173 | 5b |
| Belle Plaine | Apr 28 | Oct 10 | 165 | 5a |
| Bellevue Lock and Dam | Apr 25 | Oct 16 | 172 | 5a |
| Bloomfield | Apr 16 | Oct 22 | 188 | 5b |
| Boone | Apr 28 | Oct 12 | 165 | 5a |
| Britt | Apr 29 | Oct 7 | 161 | 5a |
| Burlington | Apr 18 | Oct 20 | 185 | 6a |
| Burlington Municipal Airport | Apr 15 | Oct 20 | 187 | 6a |
| Carroll | Apr 27 | Oct 10 | 166 | 5a |
| Cascade | Apr 28 | Oct 10 | 164 | 5a |
| Castana Experiment Farm | Apr 25 | Oct 12 | 170 | 5b |
| Cedar Rapids | Apr 28 | Oct 12 | 166 | 5a |
| Cedar Rapids Municipal Airport | Apr 27 | Oct 11 | 165 | 5a |
| Centerville | Apr 28 | Oct 14 | 168 | 5b |
| Chariton | May 5 | Oct 5 | 151 | 5b |
| Charles City | Apr 30 | Oct 6 | 157 | 5a |
| Cherokee | May 4 | Oct 4 | 152 | 5a |
| Clarinda | Apr 25 | Oct 11 | 168 | 5b |
| Clarion | Apr 30 | Oct 10 | 162 | 5a |
| Clinton | Apr 22 | Oct 16 | 175 | 5b |
| Coggon | May 3 | Oct 7 | 156 | 5a |
| Colo | Apr 24 | Oct 12 | 170 | 5a |
| Columbus Junction | Apr 26 | Oct 10 | 167 | 5b |
| Corning | Apr 27 | Oct 12 | 168 | 5b |
| Cresco | May 8 | Oct 1 | 147 | 4b |
| Creston | Apr 28 | Oct 11 | 164 | 5b |
| Dakota City | Apr 26 | Oct 12 | 169 | 5a |
| Davenport | Apr 23 | Oct 15 | 174 | 5b |
| Decorah | May 3 | Oct 7 | 157 | 5a |
| Denison | Apr 27 | Oct 11 | 166 | 5a |
| Des Moines | Apr 21 | Oct 15 | 174 | 5b |
| Des Moines International Airport | Apr 18 | Oct 20 | 184 | 5b |
| Des Moines Wsfo-Johnston | Apr 19 | Oct 18 | 179 | 5b |
| Donnellson | Apr 17 | Oct 22 | 187 | 6a |
| Dubuque Lock and Dam | Apr 19 | Oct 21 | 184 | 5a |
| Dubuque Regional Airport | Apr 28 | Oct 11 | 165 | 5a |
| Eldora | Apr 27 | Oct 10 | 165 | 5a |
| Elkader | May 8 | Oct 1 | 146 | 4b |
| Emmetsburg | Apr 27 | Oct 7 | 164 | 5a |
| Estherville | May 2 | Oct 3 | 153 | 5a |
| Estherville Municipal Airport | May 2 | Sep 30 | 150 | 5a |
| Fairfield | Apr 27 | Oct 12 | 168 | 5b |
| Fayette | May 4 | Oct 4 | 151 | 5a |
| Forest City | Apr 30 | Oct 7 | 159 | 5a |
| Fort Dodge | Apr 28 | Oct 8 | 162 | 5a |
| Fort Madison | Apr 12 | Oct 25 | 194 | 6a |
| Glenwood | Apr 23 | Oct 11 | 170 | 5b |
| Greenfield | Apr 25 | Oct 12 | 170 | 5b |
| Grinnell | May 3 | Oct 6 | 155 | 5b |
| Grundy Center | Apr 29 | Oct 9 | 160 | 5a |
| Guthrie Center | May 2 | Oct 3 | 153 | 5a |
| Guttenberg Lock and Dam | Apr 21 | Oct 18 | 178 | 5a |
| Hampton | Apr 29 | Oct 9 | 162 | 5a |
| Harlan | Apr 27 | Oct 9 | 165 | 5b |
| Hawarden | May 1 | Oct 4 | 155 | 5a |
| Holstein | Apr 30 | Oct 9 | 162 | 5a |
| Humboldt Water Plant | Apr 27 | Oct 9 | 166 | 5a |
| Ida Grove | Apr 27 | Oct 12 | 167 | 5a |
| Independence | Apr 30 | Oct 7 | 159 | 5a |
| Indianola | Apr 24 | Oct 12 | 168 | 5b |
| Iowa City | Apr 29 | Oct 9 | 162 | 5b |
| Iowa City Municipal Airport | Apr 21 | Oct 18 | 180 | 5b |
| Iowa Falls | Apr 28 | Oct 10 | 164 | 5a |
| Jefferson | Apr 26 | Oct 9 | 164 | 5b |
| Keokuk Lock Dam | Apr 10 | Oct 27 | 198 | 6a |
| Keosauqua | Apr 26 | Oct 13 | 169 | 5b |
| Knoxville | Apr 20 | Oct 19 | 180 | 5b |
| Lake Park | Apr 30 | Oct 10 | 164 | 5a |
| Lamoni | Apr 16 | Oct 20 | 187 | 5b |
| Lamoni Municipal Airport | Apr 16 | Oct 21 | 186 | 5b |
| Le Claire Lock and Dam | Apr 16 | Oct 25 | 190 | 5b |
| Le Mars | Apr 30 | Oct 4 | 157 | 5a |
| Leon | Apr 30 | Oct 8 | 161 | 5b |
| Little Sioux | May 1 | Oct 3 | 155 | 5a |
| Logan | Apr 29 | Oct 8 | 162 | 5b |
| Lowden | Apr 27 | Oct 10 | 165 | 5a |
| Manchester | May 3 | Oct 4 | 154 | 5a |
| Mapleton | May 3 | Oct 1 | 151 | 5a |
| Maquoketa | Apr 25 | Oct 14 | 171 | 5a |
| Marshalltown | Apr 28 | Oct 7 | 162 | 5a |
| Marshalltown Municipal Airport | Apr 30 | Oct 6 | 159 | 5a |
| Mason City | Apr 29 | Oct 7 | 161 | 5a |
| Mason City Municipal Airport | May 3 | Oct 1 | 150 | 5a |
| Milford | May 1 | Oct 6 | 158 | 5a |
| Mount Ayr | Apr 25 | Oct 12 | 169 | 5b |
| Mount Pleasant | Apr 30 | Oct 10 | 163 | 5b |
| Muscatine | Apr 24 | Oct 14 | 172 | 5b |
| Muscatine 2 mi N | Apr 18 | Oct 22 | 184 | 5b |
| New Hampton | May 2 | Oct 5 | 155 | 5a |
| Newton | Apr 22 | Oct 17 | 174 | 5b |
| Northwood | May 4 | Oct 4 | 152 | 5a |
| Oakland | Apr 23 | Oct 14 | 174 | 5b |
| Oelwein 1 mi E | Apr 27 | Oct 13 | 169 | 5a |
| Oelwein 2 mi S | Apr 30 | Oct 9 | 163 | 5a |
| Onawa | May 1 | Oct 3 | 154 | 5a |
| Osage | Apr 30 | Oct 9 | 163 | 5a |
| Osceola | Apr 29 | Oct 9 | 162 | 5b |
| Oskaloosa | Apr 21 | Oct 16 | 176 | 5b |
| Ottumwa Industrial Airport | Apr 23 | Oct 14 | 172 | 5b |
| Perry | Apr 25 | Oct 10 | 166 | 5a |
| Pocahontas | Apr 26 | Oct 7 | 164 | 5a |
| Postville | May 1 | Oct 3 | 153 | 5a |
| Primghar | Apr 29 | Oct 10 | 163 | 5a |
| Rathbun Dam | Apr 18 | Oct 23 | 187 | 5b |
| Red Oak | Apr 24 | Oct 13 | 169 | 5b |
| Rock Rapids | May 1 | Oct 4 | 156 | 5a |
| Rockwell City | Apr 26 | Oct 10 | 167 | 5a |
| Sac City | Apr 30 | Oct 6 | 158 | 5a |
| Sanborn | May 1 | Oct 7 | 160 | 5a |
| Sheldon | May 5 | Sep 28 | 145 | 5a |
| Shenandoah | Apr 20 | Oct 17 | 179 | 5b |
| Sibley | May 5 | Oct 3 | 152 | 4b |
| Sidney | Apr 19 | Oct 19 | 182 | 5b |
| Sigourney | Apr 24 | Oct 15 | 172 | 5b |
| Sioux Center | Apr 30 | Oct 3 | 154 | 5a |
| Sioux City ANG | Apr 29 | Oct 7 | 161 | 5a |
| Sioux City Gateway Airport | Apr 29 | Oct 5 | 159 | 5a |
| Sioux Rapids | Apr 30 | Oct 5 | 159 | 5a |
| Spencer | May 1 | Oct 3 | 154 | 5a |
| Spencer Municipal Airport | May 2 | Oct 2 | 154 | 5a |
| Spirit Lake | Apr 28 | Oct 11 | 164 | 5a |
| Stanley | May 4 | Oct 1 | 150 | 5a |
| Storm Lake | Apr 25 | Oct 13 | 170 | 5a |
| Swea City | May 4 | Oct 1 | 150 | 5a |
| Tipton | Apr 21 | Oct 15 | 175 | 5a |
| Toledo | Apr 30 | Oct 9 | 162 | 5a |
| Tripoli | Apr 29 | Oct 9 | 162 | 5a |
| Vinton | May 3 | Oct 3 | 151 | 5a |
| Washington | Apr 28 | Oct 11 | 165 | 5b |
| Waterloo Municipal Airport | Apr 27 | Oct 10 | 165 | 5a |
| Waukon | May 2 | Oct 11 | 161 | 5a |
| Webster City | May 3 | Oct 2 | 150 | 5a |
| Williamsburg | Apr 28 | Oct 9 | 164 | 5b |
| Winterset | Apr 30 | Oct 3 | 157 | 5b |
Median dates from NOAA 1991–2020 climate normals. How to read them.