Frost dates by state › Iowa
Iowa frost dates
Average last spring and first fall frost dates for Iowa’s largest cities, with each city’s USDA hardiness zone.
Reviewed October 2026
Among Iowa’s 20 largest cities, the average last spring frost ranges from Apr 16 in Bettendorf to Apr 29 in Sioux City. Elevation, distance from the coast and city heat all shift the date, so use your own ZIP code below for the closest match.
| City | Average last spring frost | Average first fall frost | Frost-free days | Hardiness zone | Weather station used |
|---|---|---|---|---|---|
| Des Moines | Apr 18 | Oct 20 | 185 | 5b | Des Moines Intl Airport, IA, 3 mi |
| Cedar Rapids | Apr 27 | Oct 11 | 167 | 5a–5b | Cedar Rapids Muni Airport, IA, 6 mi |
| Davenport | Apr 19 | Oct 22 | 186 | 5b | Rock Island L&D 15, IL, 3 mi |
| Sioux City | Apr 29 | Oct 7 | 161 | 5a | Sioux City Ang, IA, 7 mi |
| Ankeny | Apr 23 | Oct 15 | 175 | 5b | Ankeny, IA, 3 mi |
| Iowa City | Apr 21 | Oct 18 | 180 | 5b | Iowa City Muni Airport, IA, 2 mi |
| West Des Moines | Apr 18 | Oct 20 | 185 | 5b | Des Moines Intl Airport, IA, 7 mi |
| Ames | Apr 26 | Oct 8 | 165 | 5b | Ames Muni Airport, IA, 2 mi |
| Waterloo | Apr 27 | Oct 10 | 166 | 5a | Waterloo Muni Airport, IA, 5 mi |
| Council Bluffs | Apr 18 | Oct 21 | 186 | 5b–6a | Omaha Eppley Airfield, NE, 6 mi |
| Dubuque | Apr 19 | Oct 21 | 185 | 5a | Dubuque L&D 11, IA, 4 mi |
| Urbandale | Apr 19 | Oct 18 | 182 | 5b | Des Moines Wsfo-Johnston, IA, 7 mi |
| Marion | Apr 28 | Oct 12 | 167 | 5a–5b | Cedar Rapids #1, IA |
| Cedar Falls | Apr 27 | Oct 10 | 166 | 5a | Waterloo Muni Airport, IA, 4 mi |
| Bettendorf | Apr 16 | Oct 25 | 192 | 5b | Le Claire L&D 14, IA, 4 mi |
| Waukee | Apr 18 | Oct 20 | 185 | 5b | Des Moines Intl Airport, IA, 13 mi |
| Marshalltown | Apr 28 | Oct 7 | 162 | 5a | Marshalltown, IA, 2 mi |
| Mason City | Apr 29 | Oct 7 | 161 | 5a | Mason City, IA |
| Ottumwa | Apr 23 | Oct 14 | 174 | 5b | Ottumwa Industrial Airport, IA, 6 mi |
| Johnston | Apr 19 | Oct 18 | 182 | 5b | Des Moines Wsfo-Johnston, IA, 3 mi |
Frost dates are the dates after (spring) or before (fall) which the chance of a 32°F freeze is below 50%, from NOAA’s 1991–2020 U.S. Climate Normals for the weather station nearest each city’s center. Zones are from the 2023 USDA Plant Hardiness Zone Map for the ZIP codes around each city; a range means nearby ZIP codes differ. Cities are the 20 largest by Census Bureau 2024 population estimates.
An average is not a guarantee. There’s still about a 1 in 2 chance of frost after the average last spring date. Many gardeners wait an extra week or two before setting out tomatoes, peppers and basil, and keep covers handy.
Planting dates for Des Moines
Timed from Des Moines’s average last frost of Apr 18, using University of New Hampshire Extension’s planting guidance. For your exact dates, enter your ZIP code in the calendar below.
| Crop | Start seeds indoors | Plant outside |
|---|---|---|
| Tomatoes | Feb 28 to Mar 14 | Apr 25 to May 2 |
| Peppers | Feb 21 to Mar 7 | May 2 |
| Lettuce | Feb 14 to Feb 21 | Mar 21 to Mar 28 |
| Broccoli | Feb 7 to Feb 21 | Mar 21 to Apr 4 |
| Cucumbers | Mar 28 to Apr 4 | Apr 25 to May 2 |
| Basil | Mar 7 to Mar 21 | May 2 |
When to plant, for your garden
Your seed-starting and planting dates, timed from your last spring frost. Full calendar, 12 crops.
Enter your ZIP code to look up your average last frost date and hardiness zone, or type the date in yourself.
Frost dates: NOAA U.S. Climate Normals, 1991–2020. Hardiness zones: USDA Plant Hardiness Zone Map, 2023, ZIP code data from PRISM Group, Oregon State University, prism.oregonstate.edu, accessed Oct. 20, 2026.
More about frost dates
How to find your last frost date, and what your zone means · Full planting calendar · How to start seeds indoors
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