U.S. Frost Dates by Weather Station

NOAA station USC00402934 · Tennessee

Frost Dates for Erwin, TN

NOAA weather station Erwin 1 W (USC00402934), Tennessee · elevation 1720 ft (524 m) · hardiness zone 7b*

  • Lower-risk planting dateafter May 11only 1 spring in 10 still has a frost later
  • Typical last frostApril 2150% chance of a frost after it
  • Typical first fall frostOctober 2350% chance of a frost before it
  • Frost-free season183 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season at Erwin, TNSpring: a frost after April 4 in 9 years out of 10, after April 21 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before October 11 in 1 year out of 10, before October 23 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 183 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 21First frost ~Oct 23Frost season at Erwin, TNSpring: a frost after April 4 in 9 years out of 10, after April 21 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before October 11 in 1 year out of 10, before October 23 in half of the years, before November 4 in 9 years out of 10. Typical frost-free season: 183 days.JFMAMJJASONDLast frost ~Apr 21First frost ~Oct 23
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 11October 11
50% (typical)April 21October 23
90% (likely)April 4November 4
Frost-free season (32°F, 50% chance)
183 days
Hard frost (28°F), last in spring, 50% chance after
April 7
Hard frost (28°F), first in fall, 50% chance before
November 1

The last 15 years (2006–2020 normals)

Typical last frost April 19 (2 days earlier than the 30-year normal), typical first fall frost October 24 (1 day later). Frost-free season 188 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 Erwin: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 11, 20% May 5, 30% April 30, 40% April 25, 50% April 21, 60% April 18, 70% April 15, 80% April 10, 90% April 4. Observed last spring frost in recent years: 2021 April 24, 2022 April 11, 2023 April 26, 2024 April 8, 2026 March 19.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 11Apr 21Apr 42021: April 242022: April 112023: April 262024: April 82026: March 19Fall at Erwin: chance of a frost before this dateFall, chance of a frost before the date: 10% October 11, 20% October 14, 30% October 17, 40% October 21, 50% October 23, 60% October 25, 70% October 28, 80% November 1, 90% November 4. Observed first fall frost in recent years: 2021 November 6, 2022 October 19, 2023 November 1, 2025 November 1.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 11Oct 23Nov 42021: November 62022: October 192023: November 12025: November 1
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 24November 6
2022April 11October 19
2023April 26November 1
2024April 8incomplete record
2025incomplete recordNovember 1
2026March 19season not over yet

What these dates mean

Setting out tender crops on the early spring date, April 4, carries a 90 % chance of a frost later than that date, making it a gamble. The cautious spring date for tender crops is May 11, where only a 10 % chance of a later frost remains. The 50 % date is April 21, indicating an even-odds chance of a frost later than that point. The 50 % hard-frost date is April 7; a hard frost at 28 °F can damage plants that would survive a light frost.

In fall, the cautious date to finish harvesting tender crops is October 11, with a 10 % chance of a frost earlier than that date, while counting on crops until November 4 is a gamble because a frost earlier has a 90 % chance. The 50 % date is October 23, marking an even-odds chance of a frost earlier. The 50 % hard-frost date is November 1, and hard frost matters more than light frost because the lower temperature can harm vegetation that tolerates 32 °F.

How to read the probabilities

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

  • Spring: "10% after May 11" 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 11" 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 Erwin, TNNumbered nearest stations: 1 — Elizabethton, TN — 18 mi; 2 — near Bristol, TN — 23 mi; 3 — Kingsport, TN — 27 mi; 4 — Marshall, NC — 27 mi; 5 — Mount Mitchell, NC — 28 mi.NCTNVAKY25 mi · 40 km1. Elizabethton, TN — 18 mi12. near Bristol, TN — 23 mi23. Kingsport, TN — 27 mi34. Marshall, NC — 27 mi45. Mount Mitchell, NC — 28 mi5
  1. Elizabethton, TN 18 mi (28 km)
  2. near Bristol, TN 23 mi (37 km)
  3. Kingsport, TN 27 mi (43 km)
  4. Marshall, NC 27 mi (43 km)
  5. Mount Mitchell, NC 28 mi (45 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: 36.1422, -82.4261.