U.S. Frost Dates by Weather Station

NOAA station USC00156988 · Kentucky

Frost Dates for Rough River Lake, KY

NOAA weather station Rough River Lake (USC00156988), Kentucky · elevation 560 ft (171 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 5only 1 spring in 10 still has a frost later
  • Typical last frostApril 1750% chance of a frost after it
  • Typical first fall frostOctober 2350% chance of a frost before it
  • Frost-free season187 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Rough River Lake, KYSpring: a frost after March 31 in 9 years out of 10, after April 17 in half of the years, after May 5 in 1 year out of 10. Fall: the first frost comes before October 8 in 1 year out of 10, before October 23 in half of the years, before November 3 in 9 years out of 10. Typical frost-free season: 187 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 17First frost ~Oct 23Frost season at Rough River Lake, KYSpring: a frost after March 31 in 9 years out of 10, after April 17 in half of the years, after May 5 in 1 year out of 10. Fall: the first frost comes before October 8 in 1 year out of 10, before October 23 in half of the years, before November 3 in 9 years out of 10. Typical frost-free season: 187 days.JFMAMJJASONDLast frost ~Apr 17First 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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 5October 8
50% (typical)April 17October 23
90% (likely)March 31November 3
Frost-free season (32°F, 50% chance)
187 days
Hard frost (28°F), last in spring, 50% chance after
April 3
Hard frost (28°F), first in fall, 50% chance before
November 1

The last 15 years (2006–2020 normals)

Typical last frost April 16 (1 day earlier than the 30-year normal), typical first fall frost October 24 (1 day later). Frost-free season 189 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 Rough River Lake: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 5, 20% April 30, 30% April 25, 40% April 21, 50% April 17, 60% April 13, 70% April 9, 80% April 5, 90% March 31. Observed last spring frost in recent years: 2021 April 23, 2022 April 27, 2023 April 25, 2024 April 23.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 5Apr 17Mar 312021: April 232022: April 272023: April 252024: April 23Fall at Rough River Lake: chance of a frost before this dateFall, chance of a frost before the date: 10% October 8, 20% October 14, 30% October 18, 40% October 21, 50% October 23, 60% October 25, 70% October 27, 80% October 30, 90% November 3. Observed first fall frost in recent years: 2021 November 3, 2022 October 9, 2023 October 31, 2024 October 16.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 8Oct 23Nov 32021: November 32022: October 92023: October 312024: October 16
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 23November 3
2022April 27October 9
2023April 25October 31
2024April 23October 16
2025incomplete recordno data
2026no dataseason not over yet

What these dates mean

The 187 days between the 50% dates in Rough River Lake frame the central window for planting and harvesting. April 17 is the 50% date for light frost in spring and October 23 is the 50% date for light frost in fall; those dates mark even odds for a frost later (spring) or earlier (fall). The 50% hard-frost dates are April 3 in spring and November 1 in fall, showing the midpoint of the colder-than-28°F period.

May 5 carries a 10% chance of a frost later and is the cautious date for setting out tender crops, while March 31 has a 90% chance and represents a gamble. In the autumn, October 8 holds a 10% chance of a frost earlier and is the cautious date to finish harvesting tender crops, whereas November 3 has a 90% chance and is a gamble. A hard frost at 28°F can damage plants that survive a light frost at 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 5" 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 8" 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 Rough River Lake, KYNumbered nearest stations: 1 — Tell City, IN — 27 mi; 2 — near Bowling Green, KY — 45 mi; 3 — near Shepherdsville, KY — 51 mi; 4 — Boonville, IN — 51 mi; 5 — Barren River Lake, KY — 54 mi.KYIN25 mi · 40 km1. Tell City, IN — 27 mi12. near Bowling Green, KY — 45 mi23. near Shepherdsville, KY — 51 mi34. Boonville, IN — 51 mi45. Barren River Lake, KY — 54 mi5
  1. Tell City, IN 27 mi (44 km)
  2. near Bowling Green, KY 45 mi (73 km)
  3. near Shepherdsville, KY 51 mi (82 km)
  4. Boonville, IN 51 mi (82 km)
  5. Barren River Lake, KY 54 mi (87 km)

Sources

* Hardiness zone 6b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 37.6178, -86.5044.