U.S. Frost Dates by Weather Station

NOAA station USC00126989 · Indiana

Frost Dates for Plymouth, IN

NOAA weather station Plymouth (USC00126989), Indiana · elevation 815 ft (248 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 13only 1 spring in 10 still has a frost later
  • Typical last frostApril 2550% chance of a frost after it
  • Typical first fall frostOctober 2150% chance of a frost before it
  • Frost-free season178 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Plymouth, INSpring: a frost after April 12 in 9 years out of 10, after April 25 in half of the years, after May 13 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 21 in half of the years, before November 3 in 9 years out of 10. Typical frost-free season: 178 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 25First frost ~Oct 21Frost season at Plymouth, INSpring: a frost after April 12 in 9 years out of 10, after April 25 in half of the years, after May 13 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 21 in half of the years, before November 3 in 9 years out of 10. Typical frost-free season: 178 days.JFMAMJJASONDLast frost ~Apr 25First frost ~Oct 21
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.Today

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 13October 5
50% (typical)April 25October 21
90% (likely)April 12November 3
Frost-free season (32°F, 50% chance)
178 days
Hard frost (28°F), last in spring, 50% chance after
April 14
Hard frost (28°F), first in fall, 50% chance before
November 1

The last 15 years (2006–2020 normals)

Typical last frost April 26 (1 day later than the 30-year normal), typical first fall frost October 23 (2 days later). Frost-free season 179 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 Plymouth: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 13, 20% May 6, 30% May 2, 40% April 29, 50% April 25, 60% April 22, 70% April 19, 80% April 16, 90% April 12. Observed last spring frost in recent years: 2021 May 13, 2023 April 28, 2024 April 26, 2025 April 17, 2026 May 3.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 13Apr 25Apr 122021: May 132023: April 282024: April 262025: April 172026: May 3Fall at Plymouth: chance of a frost before this dateFall, chance of a frost before the date: 10% October 5, 20% October 12, 30% October 15, 40% October 18, 50% October 21, 60% October 23, 70% October 26, 80% October 31, 90% November 3. Observed first fall frost in recent years: 2021 October 27, 2022 October 20, 2023 October 31, 2024 October 17.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 5Oct 21Nov 32021: October 272022: October 202023: October 312024: 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
2021May 13October 27
2022incomplete recordOctober 20
2023April 28October 31
2024April 26October 17
2025April 17incomplete record
2026May 3season not over yet

What these dates mean

Between the two 32°F 50% dates—April 25 and October 21—there are 178 days, a span that holds the planting and harvesting window for tender crops in Plymouth. The median dates represent the point where the chance of a light frost is equal either side of the date; a gardener can expect a 50% chance of a frost later than April 25 in spring and a 50% chance of a frost earlier than October 21 in fall.

For a cautious plan, the spring light-frost date of May 13 carries a 10 % chance of frost later, making it the prudent day to set out tender crops, while the fall cautious date of October 5 has only a 10 % chance of frost earlier, marking a deadline to finish harvesting. The hard-frost 50% dates—April 14 and November 1—show when a 28 °F frost is equally likely either side, and a hard frost can damage plants that survive a 32 °F light frost, so it is a more critical threshold.

How to read the probabilities

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

  • Spring: "10% after May 13" 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 5" 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 Plymouth, INNumbered nearest stations: 1 — Lakeville, IN — 13 mi; 2 — Rochester, IN — 20 mi; 3 — Winamac, IN — 25 mi; 4 — near South Bend, IN — 25 mi; 5 — Laporte, IN — 28 mi.ILMI25 mi · 40 km1. Lakeville, IN — 13 mi12. Rochester, IN — 20 mi23. Winamac, IN — 25 mi34. near South Bend, IN — 25 mi45. Laporte, IN — 28 mi5
  1. Lakeville, IN 13 mi (22 km)
  2. Rochester, IN 20 mi (32 km)
  3. Winamac, IN 25 mi (41 km)
  4. near South Bend, IN 25 mi (41 km)
  5. Laporte, IN 28 mi (45 km)

Sources

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

Station coordinates: 41.3392, -86.3358.