U.S. Frost Dates by Weather Station

NOAA station USC00404946 · Tennessee

Frost Dates near Knoxville, TN

NOAA weather station Knoxville Experiment Station (USC00404946), Tennessee · elevation 830 ft (253 m) · hardiness zone 7b*

Knoxville is the nearest town to the station (4.8 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter April 29only 1 spring in 10 still has a frost later
  • Typical last frostApril 1150% chance of a frost after it
  • Typical first fall frostOctober 2850% chance of a frost before it
  • Frost-free season198 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season near Knoxville, TNSpring: a frost after March 26 in 9 years out of 10, after April 11 in half of the years, after April 29 in 1 year out of 10. Fall: the first frost comes before October 13 in 1 year out of 10, before October 28 in half of the years, before November 9 in 9 years out of 10. Typical frost-free season: 198 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 11First frost ~Oct 28Frost season near Knoxville, TNSpring: a frost after March 26 in 9 years out of 10, after April 11 in half of the years, after April 29 in 1 year out of 10. Fall: the first frost comes before October 13 in 1 year out of 10, before October 28 in half of the years, before November 9 in 9 years out of 10. Typical frost-free season: 198 days.JFMAMJJASONDLast frost ~Apr 11First frost ~Oct 28
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 29October 13
50% (typical)April 11October 28
90% (likely)March 26November 9
Frost-free season (32°F, 50% chance)
198 days
Hard frost (28°F), last in spring, 50% chance after
March 31
Hard frost (28°F), first in fall, 50% chance before
November 6

The last 15 years (2006–2020 normals)

Typical last frost April 11 (same as the 30-year normal), typical first fall frost October 30 (2 days later). Frost-free season 201 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 near Knoxville: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 29, 20% April 22, 30% April 19, 40% April 15, 50% April 11, 60% April 8, 70% April 5, 80% April 1, 90% March 26. Observed last spring frost in recent years: 2021 April 22, 2022 April 12, 2023 March 23, 2024 April 24, 2025 April 14.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 29Apr 11Mar 262021: April 222022: April 122023: March 232024: April 242025: April 14Fall near Knoxville: chance of a frost before this dateFall, chance of a frost before the date: 10% October 13, 20% October 19, 30% October 22, 40% October 25, 50% October 28, 60% October 31, 70% November 1, 80% November 5, 90% November 9. Observed first fall frost in recent years: 2021 November 7, 2022 October 19, 2023 November 2, 2024 October 17.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 13Oct 28Nov 92021: November 72022: October 192023: November 22024: October 17
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 12October 19
2023March 23November 2
2024April 24October 17
2025April 14incomplete record
2026incomplete recordseason not over yet

What these dates mean

The 198 days between the 50% dates in the Knoxville area and what fits into them give a useful frame for planting and harvesting. The 32°F 50% date is April 11 in spring and October 28 in fall; a gardener can expect an even chance of light frost on either side of those days. The cautious spring date is April 29, when only a 10% chance of a later frost remains, while March 26 carries a 90% chance and is a gamble for tender crops. In autumn the cautious date is October 13, with only a 10% chance that a frost has arrived earlier, whereas November 9 carries a 90% chance and is risky for late-season tender crops. A hard frost at 28°F—marked by the dates March 31 and November 6—can injure plants that would otherwise survive the lighter 32°F frost.

How to read the probabilities

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

  • Spring: "10% after April 29" 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 13" 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, TNNumbered nearest stations: 1 — Knoxville (McGhee Tyson Airport), TN — 6 mi; 2 — near Oak Ridge, TN — 18 mi; 3 — Lenoir City, TN — 19 mi; 4 — Sevierville, TN — 20 mi; 5 — Norris, TN — 23 mi.TNNCKYVA25 mi · 40 km1. Knoxville (McGhee Tyson Airport), TN — 6 mi12. near Oak Ridge, TN — 18 mi23. Lenoir City, TN — 19 mi34. Sevierville, TN — 20 mi45. Norris, TN — 23 mi5
  1. Knoxville (McGhee Tyson Airport), TN 6 mi (9 km)
  2. near Oak Ridge, TN 18 mi (29 km)
  3. Lenoir City, TN 19 mi (30 km)
  4. Sevierville, TN 20 mi (32 km)
  5. Norris, TN 23 mi (36 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: 35.8983, -83.9569.