U.S. Frost Dates by Weather Station

NOAA station USW00013891 · Tennessee

Frost Dates for Knoxville (McGhee Tyson Airport), TN

NOAA weather station Knoxville McGhee Tyson Airport (USW00013891), Tennessee · elevation 962 ft (293 m) · hardiness zone 7b*

  • Lower-risk planting dateafter April 17only 1 spring in 10 still has a frost later
  • Typical last frostApril 150% chance of a frost after it
  • Typical first fall frostNovember 250% chance of a frost before it
  • Frost-free season215 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season at Knoxville (McGhee Tyson Airport), TNSpring: a frost after March 14 in 9 years out of 10, after April 1 in half of the years, after April 17 in 1 year out of 10. Fall: the first frost comes before October 21 in 1 year out of 10, before November 2 in half of the years, before November 15 in 9 years out of 10. Typical frost-free season: 215 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 1First frost ~Nov 2Frost season at Knoxville (McGhee Tyson Airport), TNSpring: a frost after March 14 in 9 years out of 10, after April 1 in half of the years, after April 17 in 1 year out of 10. Fall: the first frost comes before October 21 in 1 year out of 10, before November 2 in half of the years, before November 15 in 9 years out of 10. Typical frost-free season: 215 days.JFMAMJJASONDLast frost ~Apr 1First frost ~Nov 2
frost likely chance fading 90% → 10% frost-free in a typical yearThe year at a glance. Blue: frost is likely; the gradient fades as the chance drops from 90% to 10%; green: the frost-free part of a typical year.

Frost dates (32°F)

Probability of frost, based on 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 17October 21
50% (typical)April 1November 2
90% (likely)March 14November 15
Frost-free season (32°F, 50% chance)
215 days
Hard frost (28°F), last in spring, 50% chance after
March 19
Hard frost (28°F), first in fall, 50% chance before
November 13

The last 15 years (2006–2020 normals)

Typical last frost April 2 (1 day later than the 30-year normal), typical first fall frost November 4 (2 days later). Frost-free season 218 days.

A shorter, more recent NOAA period. The 30-year normals above remain the main reference: 15 years carry more year-to-year noise.

Add these dates to your calendar Yearly reminders for the typical last frost, the lower-risk planting date and the typical first fall frost (.ics).

How the chance of frost changes with the date

Spring at Knoxville (McGhee Tyson Airport): chance of a frost after this dateSpring, chance of a frost after the date: 10% April 17, 20% April 12, 30% April 7, 40% April 4, 50% April 1, 60% March 29, 70% March 24, 80% March 19, 90% March 14. Observed last spring frost in recent years: 2021 April 22, 2022 April 10, 2023 March 21, 2024 March 19, 2025 March 18, 2026 March 19.Spring: last frostChance of a frost after this date10%50%90%Mar 1Apr 1May 1Apr 17Apr 1Mar 142021: April 222022: April 102023: March 212024: March 192025: March 182026: March 19Fall at Knoxville (McGhee Tyson Airport): chance of a frost before this dateFall, chance of a frost before the date: 10% October 21, 20% October 25, 30% October 28, 40% October 31, 50% November 2, 60% November 4, 70% November 7, 80% November 10, 90% November 15. Observed first fall frost in recent years: 2021 November 7, 2022 October 18, 2023 November 1, 2024 November 24, 2025 November 10.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Oct 21Nov 2Nov 152021: November 72022: October 182023: November 12024: November 242025: November 10
Two charts, because spring and fall answer different questions: in spring, the chance that a frost still comes after a date; in fall, the chance that the first frost has already come before it. NOAA publishes these odds from 10% to 90%, so the lines stop there. ◆ marks the actual date in each recent year.

What actually happened in recent years

Observed dates of the last spring and first fall frost (32°F) at this station; ◆ marks them on the charts above
YearLast spring frostFirst fall frost
2021April 22November 7
2022April 10October 18
2023March 21November 1
2024March 19November 24
2025March 18November 10
2026March 19season not over yet

What these dates mean

October 21 is the cautious fall date for Knoxville (McGhee Tyson Airport), marking the point when there is only a 10 % chance that a light frost has already begun and a good time to finish harvesting tender crops. The 50% dates, April 1 in spring and November 2 in fall, indicate the median moment when a light frost is equally likely to have occurred or not; they help a gardener gauge the overall risk window that spans 215 days between them. For setting out tender crops, the cautious spring date is April 17, when a frost later than that date has only a 10 % chance, while the cautious fall date is October 21, with the same low probability of an earlier frost. A hard frost at 28 °F is more damaging than a light frost at 32 °F because it can injure plant tissue that otherwise survives milder chilling.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after April 17" means that in about one spring out of ten a frost still happens after that date. The 90% date is the earliest: a frost after it happens in most years.
  • Fall: "10% before October 21" means that in about one fall out of ten the first frost arrives before that date.
  • 50% is the typical date: half of the years are earlier, half are later.
  • A light frost (32°F) damages tender plants; a hard frost (28°F) also stops most hardy vegetables.

Nearby weather stations

Map of weather stations near Knoxville (McGhee Tyson Airport), TNNumbered nearest stations: 1 — near Knoxville, TN — 6 mi; 2 — Lenoir City, TN — 16 mi; 3 — near Oak Ridge, TN — 19 mi; 4 — Sevierville, TN — 23 mi; 5 — Gatlinburg, TN — 27 mi.NC25 mi · 40 km1. near Knoxville, TN — 6 mi12. Lenoir City, TN — 16 mi23. near Oak Ridge, TN — 19 mi34. Sevierville, TN — 23 mi45. Gatlinburg, TN — 27 mi5
  1. near Knoxville, TN 6 mi (9 km)
  2. Lenoir City, TN 16 mi (25 km)
  3. near Oak Ridge, TN 19 mi (31 km)
  4. Sevierville, TN 23 mi (37 km)
  5. Gatlinburg, TN 27 mi (43 km)

Sources

* Hardiness zone 7b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 35.8181, -83.9858.