NOAA 1991–2020 freeze normals
Frost Dates in Iowa
Last and first frost at the 129 NOAA stations behind this site's Iowa pages.
At the middle station of the 129 in Iowa where a freeze comes every year, the last spring frost (50%) is April 28 and the first fall frost October 10, a freeze-free season of 165 days. The last frost is earliest at Mediapolis (Gladstone Dam 18, IL, April 8) and latest at Strawberry Point (Elkader 6 SSW, IA, May 8), 30 days apart. The season runs from 145 days at Sheldon to 202 at Mediapolis.
120 of these stations were also in NOAA's previous normals, for 1981–2010. Between the two, the median station's freeze-free season grew 4 days longer, with the last spring frost 1 day later and the first fall frost 4 days later; the season lengthened at 97 stations and shortened at 16. The two periods share twenty years, so the change reflects mostly 2011–2020 against 1981–1990.
Iowa places by frost date
| Place | ZIP | Last frost | First frost | Season | Winters with 32°F |
|---|---|---|---|---|---|
| Ankeny | 50023 | April 23 | October 15 | 173 d | 100% |
| Cedar Falls | 50613 | April 27 | October 10 | 165 d | 100% |
| Cedar Rapids | 52402 | April 28 | October 12 | 166 d | 100% |
| Dubuque | 52001 | April 19 | October 21 | 184 d | 100% |
| Cedar Rapids | 52404 | April 27 | October 11 | 165 d | 100% |
| Bettendorf | 52722 | April 19 | October 22 | 184 d | 100% |
| Council Bluffs | 51503 | April 18 | October 21 | 185 d | 100% |
| West Des Moines | 50266 | April 18 | October 20 | 184 d | 100% |
| Iowa City | 52240 | April 21 | October 18 | 180 d | 100% |
| Ames | 50010 | April 26 | October 8 | 164 d | 100% |
| Urbandale | 50322 | April 19 | October 18 | 179 d | 100% |
| Marshalltown | 50158 | April 28 | October 7 | 162 d | 100% |
| Ottumwa | 52501 | April 23 | October 14 | 172 d | 100% |
| Muscatine | 52761 | April 18 | October 24 | 188 d | 100% |
| Mason City | 50401 | April 29 | October 7 | 161 d | 100% |
| Fort Dodge | 50501 | April 28 | October 8 | 162 d | 100% |
| Sioux City | 51106 | April 29 | October 7 | 161 d | 100% |
| Davenport | 52806 | April 23 | October 15 | 174 d | 100% |
| Burlington | 52601 | April 15 | October 20 | 187 d | 100% |
| Clinton | 52732 | April 13 | October 26 | 195 d | 100% |
| Altoona | 50009 | April 21 | October 15 | 174 d | 100% |
| Newton | 50208 | April 22 | October 17 | 174 d | 100% |
| Indianola | 50125 | April 24 | October 12 | 168 d | 100% |
| Boone | 50036 | April 28 | October 12 | 165 d | 100% |
| Oskaloosa | 52577 | April 21 | October 16 | 176 d | 100% |
| Pella | 50219 | April 20 | October 19 | 180 d | 100% |
| Dubuque | 52003 | April 28 | October 11 | 165 d | 100% |
| Storm Lake | 50588 | April 25 | October 13 | 170 d | 100% |
| Mt Pleasant | 52641 | April 30 | October 10 | 163 d | 100% |
| Le Mars | 51031 | April 30 | October 4 | 157 d | 100% |
| Waverly | 50677 | April 29 | October 9 | 162 d | 100% |
| Fort Madison | 52627 | April 12 | October 25 | 194 d | 100% |
| Decorah | 52101 | May 3 | October 7 | 157 d | 100% |
| Spencer | 51301 | May 1 | October 3 | 154 d | 100% |
| Carroll | 51401 | April 27 | October 10 | 166 d | 100% |
| Keokuk | 52632 | April 10 | October 27 | 198 d | 100% |
| Grinnell | 50112 | May 3 | October 6 | 155 d | 100% |
| Fairfield | 52556 | April 27 | October 12 | 168 d | 100% |
| Eldridge | 52748 | April 21 | October 17 | 176 d | 100% |
| Sioux Center | 51250 | April 30 | October 3 | 154 d | 100% |
| Denison | 51442 | April 27 | October 11 | 166 d | 100% |
| Adel | 50003 | April 25 | October 10 | 166 d | 100% |
| Charles City | 50616 | April 30 | October 6 | 157 d | 100% |
| Glenwood | 51534 | April 23 | October 11 | 170 d | 100% |
| Winterset | 50273 | April 30 | October 3 | 157 d | 100% |
| Clear Lake | 50428 | May 3 | October 1 | 150 d | 100% |
| Washington | 52353 | April 28 | October 11 | 165 d | 100% |
| Creston | 50801 | April 28 | October 11 | 164 d | 100% |
| Webster City | 50595 | May 3 | October 2 | 150 d | 100% |
| Anamosa | 52205 | May 1 | October 4 | 154 d | 100% |
| Spirit Lake | 51360 | April 28 | October 11 | 164 d | 100% |
| Independence | 50644 | April 30 | October 7 | 159 d | 100% |
| Atlantic | 50022 | April 30 | October 2 | 153 d | 100% |
| Nevada | 50201 | April 24 | October 12 | 170 d | 100% |
| Maquoketa | 52060 | April 25 | October 14 | 171 d | 100% |
| Centerville | 52544 | April 28 | October 14 | 168 d | 100% |
| Manchester | 52057 | May 3 | October 4 | 154 d | 100% |
| Vinton | 52349 | May 3 | October 3 | 151 d | 100% |
| Osceola | 50213 | April 29 | October 9 | 162 d | 100% |
| De Witt | 52742 | April 22 | October 16 | 175 d | 100% |
| Bloomfield | 52537 | April 16 | October 22 | 188 d | 100% |
| Red Oak | 51566 | April 24 | October 13 | 169 d | 100% |
| Algona | 50511 | April 30 | October 6 | 160 d | 100% |
| Estherville | 51334 | May 2 | October 3 | 153 d | 100% |
| Clarinda | 51632 | April 25 | October 11 | 168 d | 100% |
| Oelwein | 50662 | April 27 | October 13 | 169 d | 100% |
| Harlan | 51537 | April 27 | October 9 | 165 d | 100% |
| Chariton | 50049 | May 5 | October 5 | 151 d | 100% |
| Iowa Falls | 50126 | April 28 | October 10 | 164 d | 100% |
| Cherokee | 51012 | May 4 | October 4 | 152 d | 100% |
| Sheldon | 51201 | May 5 | September 28 | 145 d | 100% |
| Waukon | 52172 | May 2 | October 11 | 161 d | 100% |
| New Hampton | 50659 | May 2 | October 5 | 155 d | 100% |
| Albia | 52531 | April 24 | October 16 | 173 d | 100% |
| Cresco | 52136 | May 8 | October 1 | 147 d | 100% |
| Forest City | 50436 | April 30 | October 7 | 159 d | 100% |
| Sergeant Bluff | 51054 | April 29 | October 5 | 159 d | 100% |
| Shenandoah | 51601 | April 20 | October 17 | 179 d | 100% |
| Dyersville | 52040 | April 28 | October 10 | 164 d | 100% |
| Bellevue | 52031 | April 25 | October 16 | 172 d | 100% |
| Humboldt | 50548 | April 27 | October 9 | 166 d | 100% |
| Hampton | 50441 | April 29 | October 9 | 162 d | 100% |
| Tipton | 52772 | April 21 | October 15 | 175 d | 100% |
| Jefferson | 50129 | April 26 | October 9 | 164 d | 100% |
| Osage | 50461 | April 30 | October 9 | 163 d | 100% |
| West Liberty | 52776 | April 29 | October 9 | 162 d | 100% |
| Milford | 51351 | May 1 | October 6 | 158 d | 100% |
| Missouri Valley | 51555 | April 29 | October 8 | 162 d | 100% |
| Williamsburg | 52361 | April 28 | October 9 | 164 d | 100% |
| Huxley | 50124 | April 26 | October 12 | 168 d | 100% |
| Madrid | 50156 | April 23 | October 14 | 173 d | 100% |
| Tama | 52339 | April 30 | October 9 | 162 d | 100% |
| Emmetsburg | 50536 | April 27 | October 7 | 164 d | 100% |
| Garner | 50438 | April 29 | October 7 | 161 d | 100% |
| Eagle Grove | 50533 | April 30 | October 10 | 162 d | 100% |
| Wilton | 52778 | April 18 | October 22 | 184 d | 100% |
| Sibley | 51249 | May 5 | October 3 | 152 d | 100% |
| Postville | 52162 | May 1 | October 3 | 153 d | 100% |
| Grundy Center | 50638 | April 29 | October 9 | 160 d | 100% |
| Hawarden | 51023 | May 1 | October 4 | 155 d | 100% |
| Eldora | 50627 | April 27 | October 10 | 165 d | 100% |
| Columbus Junction | 52738 | April 26 | October 10 | 167 d | 100% |
| Onawa | 51040 | May 1 | October 3 | 154 d | 100% |
| West Union | 52175 | May 4 | October 4 | 151 d | 100% |
| Wapello | 52653 | April 14 | October 24 | 190 d | 100% |
| Rockwell City | 50579 | April 26 | October 10 | 167 d | 100% |
| Mediapolis | 52637 | April 8 | October 29 | 202 d | 100% |
| Northwood | 50459 | May 4 | October 4 | 152 d | 100% |
| Belle Plaine | 52208 | April 28 | October 10 | 165 d | 100% |
| Audubon | 50025 | May 2 | October 3 | 154 d | 100% |
| Lamoni | 50140 | April 17 | October 21 | 184 d | 100% |
| Panora | 50216 | May 2 | October 3 | 153 d | 100% |
| Guttenberg | 52052 | April 21 | October 18 | 178 d | 100% |
| Central City | 52214 | May 3 | October 7 | 156 d | 100% |
| Leon | 50144 | April 30 | October 8 | 161 d | 100% |
| Sigourney | 52591 | April 24 | October 15 | 172 d | 100% |
| Lisbon | 52253 | April 27 | October 13 | 170 d | 100% |
| Parkersburg | 50665 | April 27 | October 8 | 165 d | 100% |
| Ida Grove | 51445 | April 27 | October 12 | 167 d | 100% |
| Greenfield | 50849 | April 25 | October 12 | 170 d | 100% |
| Corning | 50841 | April 27 | October 12 | 168 d | 100% |
| Corydon | 50060 | April 21 | October 19 | 178 d | 100% |
| Fairbank | 50629 | April 30 | October 9 | 163 d | 100% |
| Mount Ayr | 50854 | April 25 | October 12 | 169 d | 100% |
| Sac City | 50583 | April 30 | October 6 | 158 d | 100% |
| Strawberry Point | 52076 | May 8 | October 1 | 146 d | 100% |
| Hartley | 51346 | May 1 | October 7 | 160 d | 100% |
| Pocahontas | 50574 | April 26 | October 7 | 164 d | 100% |
| Bedford | 50833 | April 24 | October 15 | 173 d | 100% |
50% dates from NOAA NCEI U.S. Climate Normals 1991–2020, one row per station; a state page is published when at least 5 stations stand behind its pages. Where a freeze comes in fewer than nine winters in ten, the dates describe the winters that have one.