U.S. Frost Dates by Weather Station

NOAA station USC00306314 · New York

Frost Dates for Oswego, NY

NOAA weather station Oswego (USC00306314), New York · elevation 324 ft (99 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 7only 1 spring in 10 still has a frost later
  • Typical last frostApril 2250% chance of a frost after it
  • Typical first fall frostOctober 2950% chance of a frost before it
  • Frost-free season187 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Oswego, NYSpring: a frost after April 9 in 9 years out of 10, after April 22 in half of the years, after May 7 in 1 year out of 10. Fall: the first frost comes before October 9 in 1 year out of 10, before October 29 in half of the years, before November 11 in 9 years out of 10. Typical frost-free season: 187 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 22First frost ~Oct 29Frost season at Oswego, NYSpring: a frost after April 9 in 9 years out of 10, after April 22 in half of the years, after May 7 in 1 year out of 10. Fall: the first frost comes before October 9 in 1 year out of 10, before October 29 in half of the years, before November 11 in 9 years out of 10. Typical frost-free season: 187 days.JFMAMJJASONDLast frost ~Apr 22First frost ~Oct 29
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)May 7October 9
50% (typical)April 22October 29
90% (likely)April 9November 11
Frost-free season (32°F, 50% chance)
187 days
Hard frost (28°F), last in spring, 50% chance after
April 10
Hard frost (28°F), first in fall, 50% chance before
November 10

The last 15 years (2006–2020 normals)

Typical last frost April 22 (same as the 30-year normal), typical first fall frost October 31 (2 days later). Frost-free season 191 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 Oswego: 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 25, 50% April 22, 60% April 20, 70% April 18, 80% April 14, 90% April 9. Observed last spring frost in recent years: 2021 April 22, 2022 April 30, 2023 April 27, 2024 April 26, 2025 April 10, 2026 April 21.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 7Apr 22Apr 92021: April 222022: April 302023: April 272024: April 262025: April 102026: April 21Fall at Oswego: chance of a frost before this dateFall, chance of a frost before the date: 10% October 9, 20% October 17, 30% October 21, 40% October 26, 50% October 29, 60% November 1, 70% November 3, 80% November 6, 90% November 11. Observed first fall frost in recent years: 2021 November 6, 2022 November 9, 2023 November 13, 2024 November 3, 2025 October 27.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 9Oct 29Nov 112021: November 62022: November 92023: November 132024: November 32025: October 27
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 22November 6
2022April 30November 9
2023April 27November 13
2024April 26November 3
2025April 10October 27
2026April 21season not over yet

What these dates mean

The 187 days between the 50% dates in Oswego frame the period when light frosts are equally likely to occur. The median spring light-frost date is April 22 and the median fall light-frost date is October 29; each marks the point at which a frost has a 50 % chance of coming later (spring) or earlier (fall).

For a cautious plan, tender crops should be set out after the spring light-frost cautious date of May 7, which carries only a 10 % chance of a later frost, and harvested before the fall cautious date of October 9, when there is only a 10 % chance that a frost has already arrived. The hard-frost 50 % dates are April 10 in spring and November 10 in fall, and a hard frost at 28 °F can damage plants that would survive a light frost at 32 °F, making it a more severe threat.

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 9" 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 Oswego, NYNumbered nearest stations: 1 — Sodus, NY — 31 mi; 2 — near Syracuse, NY — 32 mi; 3 — Watertown (Airport), NY — 45 mi; 4 — Geneva, NY — 47 mi; 5 — Watertown, NY — 49 mi.25 mi · 40 km1. Sodus, NY — 31 mi12. near Syracuse, NY — 32 mi23. Watertown (Airport), NY — 45 mi34. Geneva, NY — 47 mi45. Watertown, NY — 49 mi5
  1. Sodus, NY 31 mi (50 km)
  2. near Syracuse, NY 32 mi (51 km)
  3. Watertown (Airport), NY 45 mi (73 km)
  4. Geneva, NY 47 mi (75 km)
  5. Watertown, NY 49 mi (79 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: 43.45, -76.5369.