Frost dates in Iowa

Across Iowa, the typical last spring frost is around Apr 28 and the first fall frost around Oct 10. Your own dates depend on where you are in the state; find your county below.

Most of the state's last spring frosts fall between Apr 20 and May 3, and its first fall frosts between Oct 3 and Oct 19.

These are the dates with a 50% chance of a 32°F frost on or after (spring) or on or before (fall), so plan tender crops a week or two after the spring date and keep row cover handy. For dates at your exact ZIP code, use the zone and frost date lookup; for what to plant when, see the planting guide by frost date.

Hardiness zones in Iowa: zone 4b, zone 5a, zone 5b, zone 6a

Frost dates by county in Iowa

CountyLast spring frostFirst fall frostGrowing season
AdairApr 25Oct 12About 170 days
AdamsApr 27Oct 12About 168 days
AllamakeeMay 2Oct 11About 162 days
AppanooseApr 28Oct 14About 169 days
AudubonMay 2Oct 3About 154 days
BentonMay 3Oct 10About 160 days
Black HawkApr 27Oct 10About 166 days
BooneApr 28Oct 12About 167 days
BremerApr 29Oct 9About 163 days
BuchananApr 30Oct 7About 160 days
Buena VistaApr 30Oct 13About 166 days
ButlerApr 27Oct 8About 164 days
CalhounApr 26Oct 10About 167 days
CarrollApr 27Oct 10About 166 days
CassApr 30Oct 2About 155 days
CedarApr 27Oct 13About 169 days
Cerro GordoApr 29Oct 7About 161 days
CherokeeMay 4Oct 4About 153 days
ChickasawMay 2Oct 5About 156 days
ClarkeApr 29Oct 9About 163 days
ClayMay 1Oct 4About 156 days
ClaytonApr 28Oct 12About 167 days
ClintonApr 22Oct 16About 177 days
CrawfordApr 27Oct 11About 167 days
DallasApr 25Oct 10About 168 days
DavisApr 16Oct 22About 189 days
DecaturApr 23Oct 17About 177 days
DelawareMay 3Oct 4About 154 days
Des MoinesApr 15Oct 20About 188 days
DickinsonApr 30Oct 10About 163 days
DubuqueApr 21Oct 18About 180 days
EmmetMay 2Oct 3About 154 days
FayetteMay 4Oct 4About 153 days
FloydApr 30Oct 6About 159 days
FranklinApr 29Oct 9About 163 days
FremontApr 19Oct 19About 183 days
GreeneApr 26Oct 9About 166 days
GrundyApr 29Oct 9About 163 days
GuthrieMay 2Oct 3About 154 days
HamiltonMay 3Oct 2About 152 days
HancockApr 29Oct 7About 161 days
HardinApr 27Oct 10About 166 days
HarrisonApr 29Oct 8About 162 days
HenryApr 30Oct 10About 163 days
HowardMay 8Oct 1About 146 days
HumboldtApr 27Oct 12About 168 days
IdaApr 30Oct 9About 162 days
IowaApr 28Oct 9About 164 days
JacksonApr 25Oct 14About 172 days
JasperApr 22Oct 17About 178 days
JeffersonApr 27Oct 12About 168 days
JohnsonApr 21Oct 18About 180 days
JonesApr 28Oct 10About 165 days
KeokukApr 24Oct 15About 174 days
KossuthApr 30Oct 6About 159 days
LeeApr 17Oct 22About 188 days
LinnApr 28Oct 12About 167 days
LouisaApr 26Oct 10About 167 days
LucasMay 5Oct 5About 153 days
LyonMay 1Oct 4About 156 days
MadisonApr 30Oct 3About 156 days
MahaskaApr 21Oct 16About 178 days
MarionApr 20Oct 19About 182 days
MarshallApr 28Oct 7About 162 days
MillsApr 23Oct 11About 171 days
MitchellApr 30Oct 9About 162 days
MononaMay 1Oct 3About 155 days
MonroeApr 24Oct 16About 175 days
MontgomeryApr 24Oct 13About 172 days
MuscatineApr 24Oct 14About 173 days
O'BrienApr 29Oct 10About 164 days
OsceolaMay 5Oct 3About 151 days
PageApr 25Oct 11About 169 days
Palo AltoApr 27Oct 7About 163 days
PlymouthApr 30Oct 4About 157 days
PocahontasApr 26Oct 7About 164 days
PolkApr 19Oct 18About 182 days
PottawattamieApr 23Oct 14About 174 days
PoweshiekMay 3Oct 10About 160 days
RinggoldApr 25Oct 12About 170 days
SacApr 30Oct 6About 159 days
ScottApr 21Oct 22About 184 days
ShelbyApr 27Oct 9About 165 days
SiouxMay 1Oct 3About 155 days
StoryApr 26Oct 12About 169 days
TamaApr 30Oct 9About 162 days
TaylorApr 24Oct 14About 173 days
UnionApr 28Oct 11About 166 days
Van BurenApr 26Oct 13About 170 days
WapelloApr 23Oct 14About 174 days
WarrenApr 24Oct 12About 171 days
WashingtonApr 28Oct 11About 166 days
WayneApr 21Oct 19About 181 days
WebsterApr 28Oct 8About 163 days
WinnebagoApr 30Oct 7About 160 days
WinneshiekMay 3Oct 7About 157 days
WoodburyApr 29Oct 7About 161 days
WorthMay 3Oct 4About 154 days
WrightApr 30Oct 10About 163 days

Source: NOAA NCEI U.S. Climate Normals 1991–2020, 50% probability of 32°F, from the weather station nearest each ZIP code; each county shows the middle value across its ZIP codes. Hills, valleys and cities can run a week or more earlier or later.

Frost dates for other states