U.S. Frost Dates by Weather Station

NOAA station USC00307134 · New York

Frost Dates for Riverhead, NY

NOAA weather station Riverhead Research Farm (USC00307134), New York · elevation 100 ft (31 m) · hardiness zone 7b*

  • Lower-risk planting dateafter April 19only 1 spring in 10 still has a frost later
  • Typical last frostApril 650% chance of a frost after it
  • Typical first fall frostNovember 950% chance of a frost before it
  • Frost-free season215 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season at Riverhead, NYSpring: a frost after March 27 in 9 years out of 10, after April 6 in half of the years, after April 19 in 1 year out of 10. Fall: the first frost comes before October 28 in 1 year out of 10, before November 9 in half of the years, before November 22 in 9 years out of 10. Typical frost-free season: 215 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 6First frost ~Nov 9Frost season at Riverhead, NYSpring: a frost after March 27 in 9 years out of 10, after April 6 in half of the years, after April 19 in 1 year out of 10. Fall: the first frost comes before October 28 in 1 year out of 10, before November 9 in half of the years, before November 22 in 9 years out of 10. Typical frost-free season: 215 days.JFMAMJJASONDLast frost ~Apr 6First frost ~Nov 9
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 19October 28
50% (typical)April 6November 9
90% (likely)March 27November 22
Frost-free season (32°F, 50% chance)
215 days
Hard frost (28°F), last in spring, 50% chance after
March 28
Hard frost (28°F), first in fall, 50% chance before
November 21

The last 15 years (2006–2020 normals)

Typical last frost April 6 (same as the 30-year normal), typical first fall frost November 10 (1 day later). Frost-free season 218 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 Riverhead: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 19, 20% April 15, 30% April 12, 40% April 9, 50% April 6, 60% April 4, 70% April 2, 80% March 31, 90% March 27. Observed last spring frost in recent years: 2021 April 4, 2022 March 30, 2023 April 10, 2024 April 26, 2025 April 18, 2026 April 20.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 19Apr 6Mar 272021: April 42022: March 302023: April 102024: April 262025: April 182026: April 20Fall at Riverhead: chance of a frost before this dateFall, chance of a frost before the date: 10% October 28, 20% November 1, 30% November 3, 40% November 6, 50% November 9, 60% November 12, 70% November 14, 80% November 18, 90% November 22. Observed first fall frost in recent years: 2021 November 7, 2022 November 15, 2023 November 13, 2024 November 10, 2025 November 7.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Oct 28Nov 9Nov 222021: November 72022: November 152023: November 132024: 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 7
2022March 30November 15
2023April 10November 13
2024April 26November 10
2025April 18November 7
2026April 20season not over yet

What these dates mean

October 28 marks the cautious fall date for Riverhead, the point at which there is only a ten percent chance that a light frost has already arrived, making it the recommended deadline to finish harvesting tender crops.

In spring the cautious date for setting out tender crops is April 19, when the probability of a later light frost is ten percent; planting earlier, such as on March 27, carries a ninety percent chance of frost and is a gamble. The 50% dates are April 6 in spring and November 9 in fall, each representing an even fifty percent chance of frost occurring later (spring) or earlier (fall).

Hard frosts at 28°F are more damaging than light frosts at 32°F, and the 50% hard-frost dates are March 28 in spring and November 21 in fall, marking when the risk of such severe cold reaches a fifty percent level.

How to read the probabilities

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

  • Spring: "10% after April 19" 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 28" 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 Riverhead, NYNumbered nearest stations: 1 — Bridgehampton, NY — 22 mi; 2 — near Islip, NY — 23 mi; 3 — near Bridgeport, CT — 25 mi; 4 — near Norwich, CT — 52 mi; 5 — near Purchase, NY — 52 mi.CTNY25 mi · 40 km1. Bridgehampton, NY — 22 mi12. near Islip, NY — 23 mi23. near Bridgeport, CT — 25 mi34. near Norwich, CT — 52 mi45. near Purchase, NY — 52 mi5
  1. Bridgehampton, NY 22 mi (35 km)
  2. near Islip, NY 23 mi (37 km)
  3. near Bridgeport, CT 25 mi (41 km)
  4. near Norwich, CT 52 mi (83 km)
  5. near Purchase, NY 52 mi (84 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: 40.9625, -72.7161.