U.S. Frost Dates by Weather Station

NOAA station USC00127298 · Indiana

Frost Dates for Rensselaer, IN

NOAA weather station Rensselaer (USC00127298), Indiana · elevation 630 ft (192 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 7only 1 spring in 10 still has a frost later
  • Typical last frostApril 2350% chance of a frost after it
  • Typical first fall frostOctober 1850% chance of a frost before it
  • Frost-free season177 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Rensselaer, INSpring: a frost after April 9 in 9 years out of 10, after April 23 in half of the years, after May 7 in 1 year out of 10. Fall: the first frost comes before October 4 in 1 year out of 10, before October 18 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 177 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 23First frost ~Oct 18Frost season at Rensselaer, INSpring: a frost after April 9 in 9 years out of 10, after April 23 in half of the years, after May 7 in 1 year out of 10. Fall: the first frost comes before October 4 in 1 year out of 10, before October 18 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 177 days.JFMAMJJASONDLast frost ~Apr 23First frost ~Oct 18
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 4
50% (typical)April 23October 18
90% (likely)April 9November 1
Frost-free season (32°F, 50% chance)
177 days
Hard frost (28°F), last in spring, 50% chance after
April 11
Hard frost (28°F), first in fall, 50% chance before
October 29

The last 15 years (2006–2020 normals)

Typical last frost April 24 (1 day later than the 30-year normal), typical first fall frost October 20 (2 days later). Frost-free season 178 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 Rensselaer: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 7, 20% May 1, 30% April 29, 40% April 26, 50% April 23, 60% April 20, 70% April 17, 80% April 13, 90% April 9. Observed last spring frost in recent years: 2021 May 12, 2022 April 27, 2023 April 27, 2024 April 25, 2025 April 16, 2026 May 2.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 7Apr 23Apr 92021: May 122022: April 272023: April 272024: April 252025: April 162026: May 2Fall at Rensselaer: chance of a frost before this dateFall, chance of a frost before the date: 10% October 4, 20% October 9, 30% October 13, 40% October 16, 50% October 18, 60% October 20, 70% October 23, 80% October 27, 90% November 1. Observed first fall frost in recent years: 2021 November 1, 2022 October 8, 2023 October 10, 2024 October 17, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 4Oct 18Nov 12021: November 12022: October 82023: October 102024: October 172025: October 23
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 12November 1
2022April 27October 8
2023April 27October 10
2024April 25October 17
2025April 16October 23
2026May 2season not over yet

What these dates mean

Setting out tender crops on April 9 in Rensselaer carries a 90 % chance of a frost later that season, making it a gamble for any gardener.

The 50 % spring median, April 23, represents a 50 % chance of a frost later than this date, while the 50 % fall median, October 18, represents a 50 % chance of a frost earlier than this date; the interval between these two 32°F dates spans 177 days. For a lower risk approach, the cautious spring date is May 7, when only a 10 % chance of a later frost remains, and the cautious fall date is October 4, when there is just a 10 % chance that a frost has already occurred.

A hard frost at 28 °F, recorded by the median dates of April 11 in spring and October 29 in fall, can damage plants more severely than a light 32 °F frost, so its timing matters especially for winter-hardier varieties.

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 4" 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 Rensselaer, INNumbered nearest stations: 1 — Lowell, IN — 27 mi; 2 — Winamac, IN — 32 mi; 3 — Watseka, IL — 32 mi; 4 — West Lafayette, IN — 32 mi; 5 — Lafayette (Purdue University Airport), IN — 37 mi.INIL25 mi · 40 km1. Lowell, IN — 27 mi12. Winamac, IN — 32 mi23. Watseka, IL — 32 mi34. West Lafayette, IN — 32 mi45. Lafayette (Purdue University Airport), IN — 37 mi5
  1. Lowell, IN 27 mi (43 km)
  2. Winamac, IN 32 mi (51 km)
  3. Watseka, IL 32 mi (51 km)
  4. West Lafayette, IN 32 mi (52 km)
  5. Lafayette (Purdue University Airport), IN 37 mi (60 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: 40.9239, -87.1753.