Frost dates for Keokuk Lock Dam 19, IA
At Keokuk Lock Dam 19, the median last spring frost (32°F) is Apr 10 and the median first fall frost is Oct 27, for a typical growing season of 198 days. For a 90% chance that the last frost has passed, wait until Apr 26. Nearby ZIP codes are in USDA hardiness zone 6a.
- Apr 10Last spring frost (median)50% chance of 32°F after this date
- Apr 26Safer planting date10% chance of 32°F after this date
- Oct 27First fall frost (median)50% chance of 32°F by this date
- 198 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 7 | Apr 22 | May 7 |
| 32°F | Mar 30 | Apr 10 | Apr 26 |
| 28°F | Mar 16 | Apr 2 | Apr 16 |
| 24°F | Mar 6 | Mar 23 | Apr 7 |
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 | Oct 1 | Oct 17 | Oct 30 |
| 32°F | Oct 10 | Oct 27 | Nov 7 |
| 28°F | Oct 24 | Nov 5 | Nov 20 |
| 24°F | Nov 2 | Nov 15 | Dec 1 |
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 | 156 days | 177 days | 197 days |
| 32°F | 177 days | 198 days | 218 days |
| 28°F | 198 days | 220 days | 241 days |
| 24°F | 216 days | 239 days | 262 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 |
|---|---|---|---|
| 52632 | 6a | -10 to -5°F | 7 km |
| 62341 | 6a | -10 to -5°F | 7 km |
| 62334 | 6a | -10 to -5°F | 11 km |
| 63430 | 6a | -10 to -5°F | 13 km |
| 62379 | 6a | -10 to -5°F | 14 km |
| 63472 | 6a | -10 to -5°F | 17 km |
| 63445 | 6a | -10 to -5°F | 29 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 USC00134381, at 40.3967, -91.3750, elevation 161 m (527 ft).
- Data quality: Standard (24+ years of data), 30 years of freeze data.
- Average days per year at or below 32°F: 117.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Fort Madison (25 km)
- Donnellson (32 km)
- Burlington 2s (47 km)
- Burlington Muni Airport (48 km)
- Keosauqua (63 km)
- Mount Pleasant 1 SSW (63 km)
- Fairfield (85 km)
- Bloomfield (96 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.