Frost dates for Glenwood 3sw, IA
At Glenwood 3sw, the median last spring frost (32°F) is Apr 23 and the median first fall frost is Oct 11, for a typical growing season of 170 days. For a 90% chance that the last frost has passed, wait until May 6. Nearby ZIP codes are in USDA hardiness zones 5b to 6a.
- Apr 23Last spring frost (median)50% chance of 32°F after this date
- May 6Safer planting date10% chance of 32°F after this date
- Oct 11First fall frost (median)50% chance of 32°F by this date
- 170 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 17 |
| 32°F | Apr 9 | Apr 23 | May 6 |
| 28°F | Mar 29 | Apr 12 | Apr 27 |
| 24°F | Mar 17 | Apr 3 | Apr 18 |
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 19 | Oct 2 | Oct 15 |
| 32°F | Sep 27 | Oct 11 | Oct 25 |
| 28°F | Oct 3 | Oct 21 | Nov 3 |
| 24°F | Oct 15 | Oct 30 | Nov 13 |
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 | 132 days | 151 days | 170 days |
| 32°F | 150 days | 170 days | 190 days |
| 28°F | 169 days | 190 days | 208 days |
| 24°F | 188 days | 209 days | 230 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 |
|---|---|---|---|
| 51561 | 5b | -15 to -10°F | 3 km |
| 51534 | 6a | -10 to -5°F | 6 km |
| 51551 | 5b | -15 to -10°F | 16 km |
| 51554 | 5b | -15 to -10°F | 17 km |
| 51571 | 6a | -10 to -5°F | 20 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 USC00133290, at 41.0097, -95.7736, elevation 299 m (980 ft).
- Data quality: Representative (10+ years), 18 years of freeze data.
- Average days per year at or below 32°F: 146.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Sidney 1sse (32 km)
- Shenandoah (44 km)
- Red Oak (45 km)
- Oakland (46 km)
- Logan (70 km)
- Clarinda (71 km)
- Atlantic 1 NE (79 km)
- Harlan (80 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.