Frost dates for Valparaiso Porter Co Muni Airport, IN
At Valparaiso Porter Co Muni Airport, the median last spring frost (32°F) is Apr 20 and the median first fall frost is Oct 26, for a typical growing season of 187 days. For a 90% chance that the last frost has passed, wait until May 7. Nearby ZIP codes are in USDA hardiness zones 5b to 6a.
- Apr 20Last spring frost (median)50% chance of 32°F after this date
- May 7Safer planting date10% chance of 32°F after this date
- Oct 26First fall frost (median)50% chance of 32°F by this date
- 187 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 18 | May 1 | May 18 |
| 32°F | Apr 6 | Apr 20 | May 7 |
| 28°F | Mar 23 | Apr 7 | Apr 23 |
| 24°F | Mar 11 | Mar 29 | Apr 10 |
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 30 | Oct 14 | Oct 28 |
| 32°F | Oct 12 | Oct 26 | Nov 8 |
| 28°F | Oct 25 | Nov 7 | Nov 23 |
| 24°F | Nov 3 | Nov 20 | Dec 6 |
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 | 144 days | 163 days | 182 days |
| 32°F | 166 days | 187 days | 207 days |
| 28°F | 192 days | 212 days | 233 days |
| 24°F | 215 days | 236 days | 259 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 |
|---|---|---|---|
| 46383 | 6a | -10 to -5°F | 1 km |
| 46302 | 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 USW00004846, at 41.4525, -87.0058, elevation 235 m (770 ft).
- Data quality: Representative (10+ years), 19 years of freeze data.
- Average days per year at or below 32°F: 125.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Wanatah 2 WNW (6 km)
- Valparaiso Wtr Wks (7 km)
- Indiana Dunes Nl (21 km)
- Wheatfield (29 km)
- Laporte (29 km)
- Knox Wastewater Plant (35 km)
- Lowell (40 km)
- Francesville (53 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.