Frost dates for Knoxville McGhee Tyson Airport, TN
At Knoxville McGhee Tyson Airport, the median last spring frost (32°F) is Apr 1 and the median first fall frost is Nov 2, for a typical growing season of 215 days. For a 90% chance that the last frost has passed, wait until Apr 17. Nearby ZIP codes are in USDA hardiness zone 7b.
- Apr 1Last spring frost (median)50% chance of 32°F after this date
- Apr 17Safer planting date10% chance of 32°F after this date
- Nov 2First fall frost (median)50% chance of 32°F by this date
- 215 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 | Mar 27 | Apr 14 | May 2 |
| 32°F | Mar 14 | Apr 1 | Apr 17 |
| 28°F | Feb 28 | Mar 19 | Apr 5 |
| 24°F | Feb 12 | Mar 6 | Mar 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 | Oct 12 | Oct 24 | Nov 5 |
| 32°F | Oct 21 | Nov 2 | Nov 15 |
| 28°F | Nov 1 | Nov 13 | Dec 1 |
| 24°F | Nov 11 | Nov 27 | Dec 22 |
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 | 170 days | 191 days | 212 days |
| 32°F | 194 days | 215 days | 236 days |
| 28°F | 217 days | 239 days | 262 days |
| 24°F | 239 days | 265 days | 295 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 |
|---|---|---|---|
| 37701 | 7b | 5 to 10°F | 3 km |
| 37777 | 7b | 5 to 10°F | 6 km |
| 37853 | 7b | 5 to 10°F | 7 km |
| 37804 | 7b | 5 to 10°F | 9 km |
| 37922 | 7b | 5 to 10°F | 11 km |
| 37803 | 7b | 5 to 10°F | 17 km |
| 37801 | 7b | 5 to 10°F | 18 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 USW00013891, at 35.8181, -83.9858, elevation 293 m (962 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 67.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Knoxville Exp. Station (9 km)
- Lenoir City (25 km)
- Townsend 5s (30 km)
- Oak Ridge Atdd (31 km)
- Oak Ridge Asos (32 km)
- Sevierville (37 km)
- Gatlinburg 2 SW (43 km)
- Norris (44 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.