Frost dates for Ames 8 WSW, IA
At Ames 8 WSW, the median last spring frost (32°F) is Apr 23 and the median first fall frost is Oct 14, for a typical growing season of 173 days. For a 90% chance that the last frost has passed, wait until May 5. Nearby ZIP codes are in USDA hardiness zones 5a to 5b.
- Apr 23Last spring frost (median)50% chance of 32°F after this date
- May 5Safer planting date10% chance of 32°F after this date
- Oct 14First fall frost (median)50% chance of 32°F by this date
- 173 daysGrowing season (median)between 32°F freezes
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 19 | May 3 | May 14 |
| 32°F | Apr 7 | Apr 23 | May 5 |
| 28°F | Mar 30 | Apr 11 | Apr 27 |
| 24°F | Mar 19 | Apr 3 | Apr 19 |
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 21 | Oct 4 | Oct 17 |
| 32°F | Sep 29 | Oct 14 | Oct 27 |
| 28°F | Oct 9 | Oct 24 | Nov 5 |
| 24°F | Oct 20 | Nov 2 | Nov 15 |
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 | 137 days | 155 days | 172 days |
| 32°F | 155 days | 173 days | 193 days |
| 28°F | 174 days | 193 days | 212 days |
| 24°F | 191 days | 211 days | 231 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 |
|---|---|---|---|
| 50152 | 5a | -20 to -15°F | 7 km |
| 50014 | 5b | -15 to -10°F | 7 km |
| 50156 | 5b | -15 to -10°F | 14 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 USC00130200, at 42.0208, -93.7742, elevation 335 m (1,099 ft).
- Data quality: Standard (24+ years of data), 30 years of freeze data.
- Average days per year at or below 32°F: 141.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Boone (10 km)
- Ames Muni Airport (13 km)
- Ames 5 SE (19 km)
- Des Moines Wsfo-Johnston (32 km)
- Ankeny (34 km)
- Perry (34 km)
- Colo (38 km)
- Webster City (50 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.