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Iowa frost dates

Across 150 NOAA climate stations in Iowa, the median last spring frost (32°F) ranges from Apr 10 at Keokuk Lock Dam 19 to May 8 at Elkader 6 Ssw; the typical station sees its last frost around Apr 28 and its first fall frost around Oct 10.

“Median” dates have a 50% chance of a later spring frost or an earlier fall frost. “10% risk” dates are the safer choice for tender plants: only 1 year in 10 has frost beyond them. Source: NOAA NCEI 1991–2020 Climate Normals. Elevation matters: within a state, frost dates can differ by a month or more between valleys and hills.

StationElevationLast frost (median)Last frost (10% risk)First frost (median)First frost (10% risk)Growing season
Albia 3 Nne880 ftApr 24May 9Oct 16Sep 29173 days
Algona1,214 ftApr 30May 11Oct 6Sep 23160 days
Allerton1,090 ftApr 21May 6Oct 19Oct 3178 days
Allison1,038 ftApr 27May 8Oct 8Sep 24165 days
Ames 5 Se870 ftApr 26May 8Oct 12Sep 26168 days
Ames 8 Wsw1,099 ftApr 23May 5Oct 14Sep 29173 days
Ames Muni AP930 ftApr 26May 9Oct 8Sep 23164 days
Anamosa 1 Wnw805 ftMay 1May 18Oct 4Sep 21154 days
Anamosa 3 Ssw906 ftApr 27May 10Oct 13Sep 30170 days
Ankeny975 ftApr 23May 6Oct 15Sep 30173 days
Atlantic 1 Ne1,152 ftApr 30May 15Oct 2Sep 17153 days
Audubon1,280 ftMay 2May 15Oct 3Sep 19154 days
Battle Creek 3NE1,380 ftMay 1May 15Oct 1Sep 18153 days
Beaconsfield1,215 ftApr 23May 6Oct 17Oct 1176 days
Bedford1,190 ftApr 24May 6Oct 15Oct 1173 days
Belle Plaine810 ftApr 28May 11Oct 10Sep 26165 days
Bellevue L&D 12603 ftApr 25May 11Oct 16Oct 1172 days
Bloomfield858 ftApr 16Apr 30Oct 22Oct 5188 days
Boone1,035 ftApr 28May 11Oct 12Sep 28165 days
Britt 3E1,220 ftApr 29May 10Oct 7Sep 24161 days
Burlington 2S690 ftApr 18May 3Oct 20Oct 6185 days
Burlington Muni AP692 ftApr 15May 1Oct 20Oct 6187 days
Carroll1,240 ftApr 27May 8Oct 10Sep 25166 days
Cascade814 ftApr 28May 12Oct 10Sep 28164 days
Castana Exp Farm1,400 ftApr 25May 7Oct 12Sep 28170 days
Cedar Rapids #1813 ftApr 28May 13Oct 12Sep 29166 days
Cedar Rapids Muni AP868 ftApr 27May 11Oct 11Sep 25165 days
Centerville905 ftApr 28May 11Oct 14Sep 26168 days
Chariton 1 E965 ftMay 5May 19Oct 5Sep 20151 days
Charles City993 ftApr 30May 14Oct 6Sep 21157 days
Cherokee1,210 ftMay 4May 17Oct 4Sep 20152 days
Clarinda980 ftApr 25May 7Oct 11Sep 26168 days
Clarion1,156 ftApr 30May 12Oct 10Sep 27162 days
Clinton #1585 ftApr 22May 8Oct 16Oct 2175 days
Coggon903 ftMay 3May 17Oct 7Sep 22156 days
Colo1,000 ftApr 24May 7Oct 12Sep 28170 days
Columbus Junction590 ftApr 26May 11Oct 10Sep 23167 days
Corning1,190 ftApr 27May 11Oct 12Sep 26168 days
Cresco 1 Ne1,255 ftMay 8May 21Oct 1Sep 19147 days
Creston 2 Sw1,296 ftApr 28May 9Oct 11Sep 24164 days
Dakota City1,110 ftApr 26May 7Oct 12Sep 29169 days
Davenport754 ftApr 23May 8Oct 15Oct 1174 days
Davenport Wfo750 ftApr 21May 7Oct 17Oct 3176 days
Decorah860 ftMay 3May 16Oct 7Sep 25157 days
Denison1,401 ftApr 27May 9Oct 11Sep 27166 days
Des Moines 17 E921 ftApr 21May 5Oct 15Sep 30174 days
Des Moines Intl AP957 ftApr 18May 2Oct 20Oct 4184 days
Des Moines Wsfo-Johnston959 ftApr 19May 3Oct 18Oct 1179 days
Donnellson705 ftApr 17May 1Oct 22Oct 10187 days
Dubuque L&D 11620 ftApr 19May 4Oct 21Oct 7184 days
Dubuque Rgnl AP1,056 ftApr 28May 12Oct 11Sep 28165 days
Eldora1,073 ftApr 27May 8Oct 10Sep 27165 days
Elkader 6 Ssw788 ftMay 8May 22Oct 1Sep 18146 days
Emmetsburg1,225 ftApr 27May 9Oct 7Sep 23164 days
Estherville 4E1,320 ftMay 2May 14Oct 3Sep 20153 days
Estherville Muni AP1,317 ftMay 2May 14Sep 30Sep 17150 days
Fairfield740 ftApr 27May 14Oct 12Sep 27168 days
Fayette1,145 ftMay 4May 17Oct 4Sep 20151 days
Forest City 2 Nne1,280 ftApr 30May 10Oct 7Sep 22159 days
Ft Dodge 5NNW1,115 ftApr 28May 9Oct 8Sep 24162 days
Ft Madison530 ftApr 12Apr 26Oct 25Oct 11194 days
Glenwood 3SW980 ftApr 23May 6Oct 11Sep 27170 days
Greenfield1,316 ftApr 25May 7Oct 12Sep 26170 days
Grinnell 3 Sw905 ftMay 3May 17Oct 6Sep 22155 days
Grundy Ctr985 ftApr 29May 12Oct 9Sep 25160 days
Guthrie Ctr1,065 ftMay 2May 17Oct 3Sep 20153 days
Guttenberg L&D 10618 ftApr 21May 6Oct 18Oct 4178 days
Hampton1,105 ftApr 29May 10Oct 9Sep 26162 days
Harlan1,270 ftApr 27May 9Oct 9Sep 24165 days
Hawarden1,190 ftMay 1May 14Oct 4Sep 21155 days
Holstein1,370 ftApr 30May 11Oct 9Sep 27162 days
Humboldt Wtp1,100 ftApr 27May 7Oct 9Sep 24166 days
Ida Grove 5NW1,320 ftApr 27May 11Oct 12Sep 27167 days
Independence #11,010 ftApr 30May 12Oct 7Sep 23159 days
Indianola 2W924 ftApr 24May 8Oct 12Sep 27168 days
Iowa City640 ftApr 29May 14Oct 9Sep 25162 days
Iowa City Muni AP650 ftApr 21May 6Oct 18Oct 4180 days
Iowa Falls1,055 ftApr 28May 11Oct 10Sep 26164 days
Jefferson1,055 ftApr 26May 8Oct 9Sep 23164 days
Keokuk Lock Dam 19527 ftApr 10Apr 26Oct 27Oct 10198 days
Keosauqua629 ftApr 26May 11Oct 13Sep 28169 days
Knoxville895 ftApr 20May 4Oct 19Oct 1180 days
Lake Park1,465 ftApr 30May 11Oct 10Sep 26164 days
Lamoni1,128 ftApr 17May 1Oct 21Oct 6184 days
Lamoni1,168 ftApr 16May 2Oct 20Oct 6187 days
Lamoni Muni AP1,131 ftApr 16May 2Oct 21Oct 6186 days
Le Claire L&D 14577 ftApr 16Apr 30Oct 25Oct 11190 days
Le Mars1,195 ftApr 30May 12Oct 4Sep 21157 days
Leon 6 Ese1,000 ftApr 30May 15Oct 8Sep 26161 days
Little Sioux 2 Nw1,025 ftMay 1May 12Oct 3Sep 20155 days
Logan990 ftApr 29May 13Oct 8Sep 23162 days
Lowden738 ftApr 27May 13Oct 10Sep 25165 days
Manchester #2990 ftMay 3May 16Oct 4Sep 22154 days
Mapleton No.21,200 ftMay 3May 16Oct 1Sep 19151 days
Maquoketa668 ftApr 25May 9Oct 14Sep 30171 days
Marshalltown870 ftApr 28May 11Oct 7Sep 22162 days
Marshalltown Muni AP974 ftApr 30May 12Oct 6Sep 22159 days
Mason City1,105 ftApr 29May 9Oct 7Sep 25161 days
Mason City Muni AP1,225 ftMay 3May 15Oct 1Sep 18150 days
Milford 4 Nw1,402 ftMay 1May 14Oct 6Sep 24158 days
Mt Ayr1,140 ftApr 25May 9Oct 12Sep 27169 days
Mt Pleasant 1 Ssw730 ftApr 30May 14Oct 10Sep 24163 days
Muscatine549 ftApr 24May 9Oct 14Oct 1172 days
Muscatine 2N680 ftApr 18May 2Oct 22Oct 8184 days
New Hampton1,148 ftMay 2May 14Oct 5Sep 23155 days
Newton960 ftApr 22May 4Oct 17Oct 1174 days
Northwood1,190 ftMay 4May 16Oct 4Sep 20152 days
Oakland1,260 ftApr 23May 5Oct 14Sep 30174 days
Oelwein 1E1,165 ftApr 27May 10Oct 13Sep 30169 days
Oelwein 2 S1,010 ftApr 30May 13Oct 9Sep 26163 days
Onawa 3NW1,060 ftMay 1May 13Oct 3Sep 21154 days
Osage1,170 ftApr 30May 12Oct 9Sep 25163 days
Osceola1,028 ftApr 29May 11Oct 9Sep 24162 days
Oskaloosa830 ftApr 21May 4Oct 16Sep 29176 days
Ottumwa Industrial AP842 ftApr 23May 7Oct 14Sep 29172 days
Perry950 ftApr 25May 8Oct 10Sep 25166 days
Pocahontas1,212 ftApr 26May 8Oct 7Sep 25164 days
Postville1,165 ftMay 1May 14Oct 3Sep 20153 days
Primghar1,520 ftApr 29May 11Oct 10Sep 26163 days
Rathbun Dam965 ftApr 18May 2Oct 23Oct 10187 days
Red Oak1,040 ftApr 24May 8Oct 13Sep 26169 days
Rock Rapids1,350 ftMay 1May 13Oct 4Sep 21156 days
Rockwell City1,214 ftApr 26May 6Oct 10Sep 27167 days
Sac City1,210 ftApr 30May 11Oct 6Sep 23158 days
Sanborn1,551 ftMay 1May 13Oct 7Sep 23160 days
Sheldon1,420 ftMay 5May 18Sep 28Sep 14145 days
Shenandoah999 ftApr 20May 3Oct 17Oct 1179 days
Sibley1,529 ftMay 5May 17Oct 3Sep 21152 days
Sidney 1SSE1,140 ftApr 19May 2Oct 19Oct 1182 days
Sigourney732 ftApr 24May 9Oct 15Sep 30172 days
Sioux City Ang1,100 ftApr 29May 11Oct 7Sep 24161 days
Sioux City Gateway AP1,095 ftApr 29May 14Oct 5Sep 22159 days
Sioux Ctr 2 Se1,360 ftApr 30May 12Oct 3Sep 19154 days
Sioux Rapids 4 E1,420 ftApr 30May 11Oct 5Sep 22159 days
Spencer 1 N1,326 ftMay 1May 14Oct 3Sep 20154 days
Spencer Muni AP1,338 ftMay 2May 15Oct 2Sep 18154 days
Spirit Lake1,420 ftApr 28May 9Oct 11Sep 27164 days
Stanley1,114 ftMay 4May 15Oct 1Sep 16150 days
Storm Lake1,442 ftApr 25May 7Oct 13Oct 1170 days
Swea City 5N1,180 ftMay 4May 14Oct 1Sep 18150 days
Tipton820 ftApr 21May 4Oct 15Oct 1175 days
Toledo 3N935 ftApr 30May 11Oct 9Sep 26162 days
Tripoli1,055 ftApr 29May 9Oct 9Sep 25162 days
Vinton850 ftMay 3May 17Oct 3Sep 20151 days
Washington687 ftApr 28May 11Oct 11Sep 25165 days
Waterloo Muni AP868 ftApr 27May 10Oct 10Sep 26165 days
Waukon1,275 ftMay 2May 16Oct 11Sep 28161 days
Webster City1,072 ftMay 3May 16Oct 2Sep 18150 days
Williamsburg 1E780 ftApr 28May 12Oct 9Sep 24164 days
Winterset 1S1,100 ftApr 30May 11Oct 3Sep 20157 days
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