U.S. Frost Dates by Weather Station

NOAA station USC00126580 · Indiana

Frost Dates near Oolitic, IN

NOAA weather station Oolitic Purdue Experiment Farm (USC00126580), Indiana · elevation 652 ft (199 m) · hardiness zone 6b*

Oolitic is the nearest town to the station (1.7 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 May 7only 1 spring in 10 still has a frost later
  • Typical last frostApril 2050% chance of a frost after it
  • Typical first fall frostOctober 2050% chance of a frost before it
  • Frost-free season181 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season near Oolitic, INSpring: a frost after April 6 in 9 years out of 10, after April 20 in half of the years, after May 7 in 1 year out of 10. Fall: the first frost comes before October 6 in 1 year out of 10, before October 20 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 181 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 20First frost ~Oct 20Frost season near Oolitic, INSpring: a frost after April 6 in 9 years out of 10, after April 20 in half of the years, after May 7 in 1 year out of 10. Fall: the first frost comes before October 6 in 1 year out of 10, before October 20 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 181 days.JFMAMJJASONDLast frost ~Apr 20First frost ~Oct 20
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)May 7October 6
50% (typical)April 20October 20
90% (likely)April 6October 30
Frost-free season (32°F, 50% chance)
181 days
Hard frost (28°F), last in spring, 50% chance after
April 7
Hard frost (28°F), first in fall, 50% chance before
October 30

The last 15 years (2006–2020 normals)

Typical last frost April 19 (1 day earlier than the 30-year normal), typical first fall frost October 23 (3 days later). Frost-free season 186 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 Oolitic: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 7, 20% May 1, 30% April 28, 40% April 24, 50% April 20, 60% April 17, 70% April 14, 80% April 9, 90% April 6. Observed last spring frost in recent years: 2022 April 20, 2023 April 26, 2024 April 23, 2025 April 13, 2026 May 4.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 7Apr 20Apr 62022: April 202023: April 262024: April 232025: April 132026: May 4Fall near Oolitic: chance of a frost before this dateFall, chance of a frost before the date: 10% October 6, 20% October 11, 30% October 14, 40% October 16, 50% October 20, 60% October 22, 70% October 24, 80% October 27, 90% October 30. Observed first fall frost in recent years: 2022 October 9, 2023 October 31, 2024 October 17, 2025 October 24.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 6Oct 20Oct 302022: October 92023: October 312024: October 172025: October 24
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
2021incomplete recordincomplete record
2022April 20October 9
2023April 26October 31
2024April 23October 17
2025April 13October 24
2026May 4season not over yet

What these dates mean

The early spring option of setting out tender crops on April 6 carries a 90 % chance of a light frost later, so it is a gamble for growers in the Oolitic area. In contrast, the cautious spring date of May 7 has only a 10 % chance of a light frost later, providing a much lower risk.

The 50% date of April 20 means there is a 50 % chance of a light frost later than this date, while the fall 50% date of October 20 means there is a 50 % chance of a light frost earlier than this date. For a cautious fall plan, October 6 is used because it carries only a 10 % chance of a light frost earlier. The 50% hard-frost dates are April 7 and October 30.

A hard frost at 28 °F can injure plants that would otherwise 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 7" 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 6" 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 Oolitic, INNumbered nearest stations: 1 — near Bloomington, IN — 20 mi; 2 — Paoli, IN — 23 mi; 3 — Shoals, IN — 27 mi; 4 — Spencer, IN — 30 mi; 5 — near French Lick, IN — 31 mi.ILKY25 mi · 40 km1. near Bloomington, IN — 20 mi12. Paoli, IN — 23 mi23. Shoals, IN — 27 mi34. Spencer, IN — 30 mi45. near French Lick, IN — 31 mi5
  1. near Bloomington, IN 20 mi (32 km)
  2. Paoli, IN 23 mi (37 km)
  3. Shoals, IN 27 mi (43 km)
  4. Spencer, IN 30 mi (48 km)
  5. near French Lick, IN 31 mi (50 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: 38.8878, -86.5519.