Frost dates for Spencer 1 N, IA
At Spencer 1 N, the median last spring frost (32°F) is May 1 and the median first fall frost is Oct 3, for a typical growing season of 154 days. For a 90% chance that the last frost has passed, wait until May 14. Nearby ZIP codes are in USDA hardiness zone 5a.
- May 1Last spring frost (median)50% chance of 32°F after this date
- May 14Safer planting date10% chance of 32°F after this date
- Oct 3First fall frost (median)50% chance of 32°F by this date
- 154 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 29 | May 10 | May 23 |
| 32°F | Apr 18 | May 1 | May 14 |
| 28°F | Apr 8 | Apr 22 | May 5 |
| 24°F | Mar 31 | Apr 12 | Apr 27 |
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 11 | Sep 24 | Oct 7 |
| 32°F | Sep 20 | Oct 3 | Oct 17 |
| 28°F | Sep 28 | Oct 14 | Oct 27 |
| 24°F | Oct 10 | Oct 24 | Nov 5 |
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 | 119 days | 137 days | 155 days |
| 32°F | 135 days | 154 days | 173 days |
| 28°F | 152 days | 174 days | 193 days |
| 24°F | 173 days | 193 days | 214 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 |
|---|---|---|---|
| 51301 | 5a | -20 to -15°F | 1 km |
| 51340 | 5a | -20 to -15°F | 8 km |
| 51333 | 5a | -20 to -15°F | 12 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 USC00137844, at 43.1653, -95.1467, elevation 404 m (1,326 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 161.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Spencer Muni Airport (4 km)
- Milford 4 NW (24 km)
- Spirit Lake (29 km)
- Sioux Rapids 4 E (31 km)
- Lake Park (35 km)
- Emmetsburg (38 km)
- Primghar (40 km)
- Sanborn (42 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.