U.S. Frost Dates by Weather Station

NOAA station USW00004781 · New York

Frost Dates near Islip, NY

NOAA weather station Islip Li MacArthur Airport (USW00004781), New York · elevation 84 ft (26 m) · hardiness zone 7b*

Islip is the nearest town to the station (7.2 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 April 25only 1 spring in 10 still has a frost later
  • Typical last frostApril 1050% chance of a frost after it
  • Typical first fall frostNovember 250% chance of a frost before it
  • Frost-free season207 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season near Islip, NYSpring: a frost after March 31 in 9 years out of 10, after April 10 in half of the years, after April 25 in 1 year out of 10. Fall: the first frost comes before October 18 in 1 year out of 10, before November 2 in half of the years, before November 15 in 9 years out of 10. Typical frost-free season: 207 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 10First frost ~Nov 2Frost season near Islip, NYSpring: a frost after March 31 in 9 years out of 10, after April 10 in half of the years, after April 25 in 1 year out of 10. Fall: the first frost comes before October 18 in 1 year out of 10, before November 2 in half of the years, before November 15 in 9 years out of 10. Typical frost-free season: 207 days.JFMAMJJASONDLast frost ~Apr 10First frost ~Nov 2
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)April 25October 18
50% (typical)April 10November 2
90% (likely)March 31November 15
Frost-free season (32°F, 50% chance)
207 days
Hard frost (28°F), last in spring, 50% chance after
March 30
Hard frost (28°F), first in fall, 50% chance before
November 14

The last 15 years (2006–2020 normals)

Typical last frost April 9 (1 day earlier than the 30-year normal), typical first fall frost November 4 (2 days later). Frost-free season 209 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 Islip: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 25, 20% April 20, 30% April 16, 40% April 13, 50% April 10, 60% April 7, 70% April 5, 80% April 3, 90% March 31. Observed last spring frost in recent years: 2021 April 4, 2022 March 30, 2023 April 3, 2024 March 24, 2025 April 9, 2026 April 20.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 25Apr 10Mar 312021: April 42022: March 302023: April 32024: March 242025: April 92026: April 20Fall near Islip: chance of a frost before this dateFall, chance of a frost before the date: 10% October 18, 20% October 24, 30% October 28, 40% October 31, 50% November 2, 60% November 4, 70% November 7, 80% November 11, 90% November 15. Observed first fall frost in recent years: 2021 November 6, 2022 November 15, 2023 November 2, 2024 November 10, 2025 November 7.Fall: first frostChance of a frost before this date10%50%90%Nov 1Oct 18Nov 2Nov 152021: November 62022: November 152023: November 22024: November 102025: November 7
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 4November 6
2022March 30November 15
2023April 3November 2
2024March 24November 10
2025April 9November 7
2026April 20season not over yet

What these dates mean

April 25 is the cautious spring date for the Islip area; with only a 10 % chance of a light frost later, a gardener can confidently set out tender crops on that day. The 50 % light-frost date in spring is April 10, meaning there is an even chance of a frost occurring after that point. In fall, October 18 serves as the cautious date, offering just a 10 % chance that a light frost has arrived earlier, so harvesting tender crops should be finished by then. The 50 % light-frost date in fall is November 2, indicating an even chance of a frost before that day. The 50 % hard-frost dates are March 30 in spring and November 14 in fall; hard frosts at 28 °F can damage plants more severely than the 32 °F light frosts because the lower temperature causes greater tissue injury.

How to read the probabilities

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

  • Spring: "10% after April 25" 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 18" 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 Islip, NYNumbered nearest stations: 1 — Riverhead, NY — 23 mi; 2 — near Bridgeport, CT — 25 mi; 3 — New York (JFK Airport), NY — 36 mi; 4 — near Purchase, NY — 37 mi; 5 — New York (LaGuardia Airport), NY — 41 mi.NYCTNJ25 mi · 40 km1. Riverhead, NY — 23 mi12. near Bridgeport, CT — 25 mi23. New York (JFK Airport), NY — 36 mi34. near Purchase, NY — 37 mi45. New York (LaGuardia Airport), NY — 41 mi5
  1. Riverhead, NY 23 mi (37 km)
  2. near Bridgeport, CT 25 mi (41 km)
  3. New York (JFK Airport), NY 36 mi (58 km)
  4. near Purchase, NY 37 mi (59 km)
  5. New York (LaGuardia Airport), NY 41 mi (66 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: 40.7939, -73.1017.