Frost dates for Ames Muni Airport, IA
At Ames Muni Airport, the median last spring frost (32°F) is Apr 26 and the median first fall frost is Oct 8, for a typical growing season of 164 days. For a 90% chance that the last frost has passed, wait until May 9. Nearby ZIP codes are in USDA hardiness zones 5a to 5b.
- Apr 26Last spring frost (median)50% chance of 32°F after this date
- May 9Safer planting date10% chance of 32°F after this date
- Oct 8First fall frost (median)50% chance of 32°F by this date
- 164 daysGrowing season (median)between 32°F freezes
USDA hardiness zone 5b (-15 to -10°F) · see all zone 5b frost dates
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Apr 21 | May 5 | May 17 |
| 32°F | Apr 11 | Apr 26 | May 9 |
| 28°F | Apr 1 | Apr 14 | May 1 |
| 24°F | Mar 17 | Apr 4 | Apr 21 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Sep 15 | Sep 28 | Oct 11 |
| 32°F | Sep 23 | Oct 8 | Oct 21 |
| 28°F | Oct 4 | Oct 19 | Oct 31 |
| 24°F | Oct 16 | Oct 29 | Nov 10 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 127 days | 146 days | 163 days |
| 32°F | 144 days | 164 days | 184 days |
| 28°F | 164 days | 184 days | 205 days |
| 24°F | 184 days | 204 days | 227 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 50013 | 5b | -15 to -10°F | 4 km |
| 50012 | 5b | -15 to -10°F | 5 km |
| 50010 | 5b | -15 to -10°F | 5 km |
| 50134 | 5b | -15 to -10°F | 7 km |
| 50105 | 5b | -15 to -10°F | 14 km |
| 50248 | 5a | -20 to -15°F | 22 km |
| 50231 | 5a | -20 to -15°F | 27 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USW00094989, at 41.9922, -93.6217, elevation 284 m (930 ft).
- Data quality: Standard (24+ years of data), 24 years of freeze data.
- Average days per year at or below 32°F: 147.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Ames 5 SE (6 km)
- Ames 8 WSW (13 km)
- Boone (23 km)
- Colo (25 km)
- Ankeny (29 km)
- Des Moines Wsfo-Johnston (30 km)
- Perry (44 km)
- Des Moines Intl Airport (51 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.