Iowa Frost Dates: Last and First Frost by Town

150 NOAA weather stations · 1991–2020 U.S. Climate Normals · Data updated 2026-10-29

Quick answer

Across Iowa's 150 NOAA stations with regular frost, the median last spring frost is April 28 and the median first fall frost is October 10. Last frost dates range from April 10 at Keokuk Lock Dam 19 to May 8 at Elkader 6 SSW, so enter your ZIP code below for the station nearest you.

How frost dates vary across Iowa

North vs south: stations in the northern third of the state (north of 42.5°N) reach their median last frost about 7 days later than the southern third (south of 41.6°N).
Safety margin: the median 10%-risk date (May 11) is about 13 days after the median last frost. Waiting until then cuts the chance of a killing frost on tender transplants from 1 in 2 to 1 in 10.

Frost dates at Iowa's major weather stations

These National Weather Service stations, mostly at airports, have the longest and most complete records in the state.


Ames Municipal Airport	930	Apr 26	May 9	Oct 8	164
Burlington Municipal Airport	692	Apr 15	May 1	Oct 20	187
Cedar Rapids Municipal Airport	868	Apr 27	May 11	Oct 11	165
Davenport	754	Apr 23	May 8	Oct 15	174
Des Moines 17 E	921	Apr 21	May 5	Oct 15	174
Des Moines Intl Airport	957	Apr 18	May 2	Oct 20	184
Dubuque Regional Airport	1,056	Apr 28	May 12	Oct 11	165
Estherville Municipal Airport	1,317	May 2	May 14	Sep 30	150
Iowa City Municipal Airport	650	Apr 21	May 6	Oct 18	180
Lamoni	1,168	Apr 16	May 2	Oct 20	187
Lamoni Municipal Airport	1,131	Apr 16	May 2	Oct 21	186
Marshalltown Municipal Airport	974	Apr 30	May 12	Oct 6	159
Mason City Municipal Airport	1,225	May 3	May 15	Oct 1	150
Ottumwa Industrial Airport	842	Apr 23	May 7	Oct 14	172
Sioux City Gateway Airport	1,095	Apr 29	May 14	Oct 5	159
Spencer Municipal Airport	1,338	May 2	May 15	Oct 2	154
Waterloo Municipal Airport	868	Apr 27	May 10	Oct 10	165

All 150 stations in Iowa

Last frost and first frost are medians: a 50% chance of a 32°F night after (spring) or before (fall) that date. 10% risk is the spring date with only a 1-in-10 chance of a later frost. Click a column to sort.

Filter by station name


Albia 3 NNE	880	Apr 24	May 9	Oct 16	173
Algona	1,214	Apr 30	May 11	Oct 6	160
Allerton	1,090	Apr 21	May 6	Oct 19	178
Allison	1,038	Apr 27	May 8	Oct 8	165
Ames 5 SE	870	Apr 26	May 8	Oct 12	168
Ames 8 WSW	1,099	Apr 23	May 5	Oct 14	173
Ames Municipal Airport	930	Apr 26	May 9	Oct 8	164
Anamosa 1 WNW	805	May 1	May 18	Oct 4	154
Anamosa 3 SSW	906	Apr 27	May 10	Oct 13	170
Ankeny	975	Apr 23	May 6	Oct 15	173
Atlantic 1 NE	1,152	Apr 30	May 15	Oct 2	153
Audubon	1,280	May 2	May 15	Oct 3	154
Battle Creek 3NE	1,380	May 1	May 15	Oct 1	153
Beaconsfield	1,215	Apr 23	May 6	Oct 17	176
Bedford	1,190	Apr 24	May 6	Oct 15	173
Belle Plaine	810	Apr 28	May 11	Oct 10	165
Bellevue L&d 12	603	Apr 25	May 11	Oct 16	172
Bloomfield	858	Apr 16	Apr 30	Oct 22	188
Boone	1,035	Apr 28	May 11	Oct 12	165
Britt 3E	1,220	Apr 29	May 10	Oct 7	161
Burlington 2S	690	Apr 18	May 3	Oct 20	185
Burlington Municipal Airport	692	Apr 15	May 1	Oct 20	187
Carroll	1,240	Apr 27	May 8	Oct 10	166
Cascade	814	Apr 28	May 12	Oct 10	164
Castana Experiment Farm	1,400	Apr 25	May 7	Oct 12	170
Cedar Rapids #1	813	Apr 28	May 13	Oct 12	166
Cedar Rapids Municipal Airport	868	Apr 27	May 11	Oct 11	165
Centerville	905	Apr 28	May 11	Oct 14	168
Chariton 1 E	965	May 5	May 19	Oct 5	151
Charles City	993	Apr 30	May 14	Oct 6	157
Cherokee	1,210	May 4	May 17	Oct 4	152
Clarinda	980	Apr 25	May 7	Oct 11	168
Clarion	1,156	Apr 30	May 12	Oct 10	162
Clinton #1	585	Apr 22	May 8	Oct 16	175
Coggon	903	May 3	May 17	Oct 7	156
Colo	1,000	Apr 24	May 7	Oct 12	170
Columbus Junction	590	Apr 26	May 11	Oct 10	167
Corning	1,190	Apr 27	May 11	Oct 12	168
Cresco 1 NE	1,255	May 8	May 21	Oct 1	147
Creston 2 SW	1,296	Apr 28	May 9	Oct 11	164
Dakota City	1,110	Apr 26	May 7	Oct 12	169
Davenport	754	Apr 23	May 8	Oct 15	174
Davenport WFO	750	Apr 21	May 7	Oct 17	176
Decorah	860	May 3	May 16	Oct 7	157
Denison	1,401	Apr 27	May 9	Oct 11	166
Des Moines 17 E	921	Apr 21	May 5	Oct 15	174
Des Moines Intl Airport	957	Apr 18	May 2	Oct 20	184
Des Moines Wsfo-johnston	959	Apr 19	May 3	Oct 18	179
Donnellson	705	Apr 17	May 1	Oct 22	187
Dubuque L&d 11	620	Apr 19	May 4	Oct 21	184
Dubuque Regional Airport	1,056	Apr 28	May 12	Oct 11	165
Eldora	1,073	Apr 27	May 8	Oct 10	165
Elkader 6 SSW	788	May 8	May 22	Oct 1	146
Emmetsburg	1,225	Apr 27	May 9	Oct 7	164
Estherville 4E	1,320	May 2	May 14	Oct 3	153
Estherville Municipal Airport	1,317	May 2	May 14	Sep 30	150
Fairfield	740	Apr 27	May 14	Oct 12	168
Fayette	1,145	May 4	May 17	Oct 4	151
Forest City 2 NNE	1,280	Apr 30	May 10	Oct 7	159
Fort Dodge 5NNW	1,115	Apr 28	May 9	Oct 8	162
Fort Madison	530	Apr 12	Apr 26	Oct 25	194
Glenwood 3SW	980	Apr 23	May 6	Oct 11	170
Greenfield	1,316	Apr 25	May 7	Oct 12	170
Grinnell 3 SW	905	May 3	May 17	Oct 6	155
Grundy Center	985	Apr 29	May 12	Oct 9	160
Guthrie Center	1,065	May 2	May 17	Oct 3	153
Guttenberg L&d 10	618	Apr 21	May 6	Oct 18	178
Hampton	1,105	Apr 29	May 10	Oct 9	162
Harlan	1,270	Apr 27	May 9	Oct 9	165
Hawarden	1,190	May 1	May 14	Oct 4	155
Holstein	1,370	Apr 30	May 11	Oct 9	162
Humboldt Wtp	1,100	Apr 27	May 7	Oct 9	166
Ida Grove 5NW	1,320	Apr 27	May 11	Oct 12	167
Independence #1	1,010	Apr 30	May 12	Oct 7	159
Indianola 2W	924	Apr 24	May 8	Oct 12	168
Iowa City	640	Apr 29	May 14	Oct 9	162
Iowa City Municipal Airport	650	Apr 21	May 6	Oct 18	180
Iowa Falls	1,055	Apr 28	May 11	Oct 10	164
Jefferson	1,055	Apr 26	May 8	Oct 9	164
Keokuk Lock Dam 19	527	Apr 10	Apr 26	Oct 27	198
Keosauqua	629	Apr 26	May 11	Oct 13	169
Knoxville	895	Apr 20	May 4	Oct 19	180
Lake Park	1,465	Apr 30	May 11	Oct 10	164
Lamoni	1,128	Apr 17	May 1	Oct 21	184
Lamoni	1,168	Apr 16	May 2	Oct 20	187
Lamoni Municipal Airport	1,131	Apr 16	May 2	Oct 21	186
Le Claire L&d 14	577	Apr 16	Apr 30	Oct 25	190
Le Mars	1,195	Apr 30	May 12	Oct 4	157
Leon 6 ESE	1,000	Apr 30	May 15	Oct 8	161
Little Sioux 2 NW	1,025	May 1	May 12	Oct 3	155
Logan	990	Apr 29	May 13	Oct 8	162
Lowden	738	Apr 27	May 13	Oct 10	165
Manchester #2	990	May 3	May 16	Oct 4	154
Mapleton No.2	1,200	May 3	May 16	Oct 1	151
Maquoketa	668	Apr 25	May 9	Oct 14	171
Marshalltown	870	Apr 28	May 11	Oct 7	162
Marshalltown Municipal Airport	974	Apr 30	May 12	Oct 6	159
Mason City	1,105	Apr 29	May 9	Oct 7	161
Mason City Municipal Airport	1,225	May 3	May 15	Oct 1	150
Milford 4 NW	1,402	May 1	May 14	Oct 6	158
Mount Ayr	1,140	Apr 25	May 9	Oct 12	169
Mount Pleasant 1 SSW	730	Apr 30	May 14	Oct 10	163
Muscatine	549	Apr 24	May 9	Oct 14	172
Muscatine 2N	680	Apr 18	May 2	Oct 22	184
New Hampton	1,148	May 2	May 14	Oct 5	155
Newton	960	Apr 22	May 4	Oct 17	174
Northwood	1,190	May 4	May 16	Oct 4	152
Oakland	1,260	Apr 23	May 5	Oct 14	174
Oelwein 1E	1,165	Apr 27	May 10	Oct 13	169
Oelwein 2 S	1,010	Apr 30	May 13	Oct 9	163
Onawa 3NW	1,060	May 1	May 13	Oct 3	154
Osage	1,170	Apr 30	May 12	Oct 9	163
Osceola	1,028	Apr 29	May 11	Oct 9	162
Oskaloosa	830	Apr 21	May 4	Oct 16	176
Ottumwa Industrial Airport	842	Apr 23	May 7	Oct 14	172
Perry	950	Apr 25	May 8	Oct 10	166
Pocahontas	1,212	Apr 26	May 8	Oct 7	164
Postville	1,165	May 1	May 14	Oct 3	153
Primghar	1,520	Apr 29	May 11	Oct 10	163
Rathbun Dam	965	Apr 18	May 2	Oct 23	187
Red Oak	1,040	Apr 24	May 8	Oct 13	169
Rock Rapids	1,350	May 1	May 13	Oct 4	156
Rockwell City	1,214	Apr 26	May 6	Oct 10	167
Sac City	1,210	Apr 30	May 11	Oct 6	158
Sanborn	1,551	May 1	May 13	Oct 7	160
Sheldon	1,420	May 5	May 18	Sep 28	145
Shenandoah	999	Apr 20	May 3	Oct 17	179
Sibley	1,529	May 5	May 17	Oct 3	152
Sidney 1SSE	1,140	Apr 19	May 2	Oct 19	182
Sigourney	732	Apr 24	May 9	Oct 15	172
Sioux Center 2 SE	1,360	Apr 30	May 12	Oct 3	154
Sioux City Ang	1,100	Apr 29	May 11	Oct 7	161
Sioux City Gateway Airport	1,095	Apr 29	May 14	Oct 5	159
Sioux Rapids 4 E	1,420	Apr 30	May 11	Oct 5	159
Spencer 1 N	1,326	May 1	May 14	Oct 3	154
Spencer Municipal Airport	1,338	May 2	May 15	Oct 2	154
Spirit Lake	1,420	Apr 28	May 9	Oct 11	164
Stanley	1,114	May 4	May 15	Oct 1	150
Storm Lake	1,442	Apr 25	May 7	Oct 13	170
Swea City 5N	1,180	May 4	May 14	Oct 1	150
Tipton	820	Apr 21	May 4	Oct 15	175
Toledo 3N	935	Apr 30	May 11	Oct 9	162
Tripoli	1,055	Apr 29	May 9	Oct 9	162
Vinton	850	May 3	May 17	Oct 3	151
Washington	687	Apr 28	May 11	Oct 11	165
Waterloo Municipal Airport	868	Apr 27	May 10	Oct 10	165
Waukon	1,275	May 2	May 16	Oct 11	161
Webster City	1,072	May 3	May 16	Oct 2	150
Williamsburg 1E	780	Apr 28	May 12	Oct 9	164
Winterset 1S	1,100	Apr 30	May 11	Oct 3	157

Frequently asked questions

When is the last frost in Iowa?

The median last spring frost (32°F) across Iowa's NOAA weather stations is April 28, based on 1991–2020 climate normals. It ranges from April 10 at Keokuk Lock Dam 19 to May 8 at Elkader 6 SSW. For a safer planting date, use the 10%-risk date; the state median for that is May 11.

When is the first frost in Iowa?

The median first fall frost across Iowa's stations is October 10. The earliest median first frost is September 28 at Sheldon, and the latest is October 27 at Keokuk Lock Dam 19.

How long is the growing season in Iowa?

The median frost-free season is 164 days across Iowa's stations, from 145 days at Sheldon to 198 days at Keokuk Lock Dam 19.

When should I plant tomatoes in Iowa?

Plant tomatoes outdoors after your local last frost, ideally after the 10%-risk date when nights stay above 50°F. At a typical Iowa station that means starting seeds indoors 6–8 weeks before April 28 and transplanting from about May 11. Check your ZIP code, because dates vary by weeks across the state.

How to use these dates

Frost dates are 30-year averages from NOAA, not forecasts. Use them to plan seed starting and planting, then watch the 10-day forecast as the date approaches. Cold air settles in valleys and low spots, so a garden at the bottom of a slope can frost a week or more later in spring than the nearest station shows.

Ready to plan? The planting calendar by ZIP code turns these dates into start-indoors, transplant and sowing dates for 30 crops.

Sources and method

Dates are the 32°F freeze probabilities published in the NOAA NCEI 1991–2020 U.S. Climate Normals for each station. Station names are NOAA's, lightly expanded for readability. See the methodology or download the full table.