U.S. Frost Dates by Weather Station

NOAA station USC00199972 · Massachusetts

Frost Dates for Worthington, MA

NOAA weather station Worthington (USC00199972), Massachusetts · elevation 1285 ft (392 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 26only 1 spring in 10 still has a frost later
  • Typical last frostMay 1350% chance of a frost after it
  • Typical first fall frostOctober 250% chance of a frost before it
  • Frost-free season144 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Worthington, MASpring: a frost after April 29 in 9 years out of 10, after May 13 in half of the years, after May 26 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 2 in half of the years, before October 15 in 9 years out of 10. Typical frost-free season: 144 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 13First frost ~Oct 2Frost season at Worthington, MASpring: a frost after April 29 in 9 years out of 10, after May 13 in half of the years, after May 26 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 2 in half of the years, before October 15 in 9 years out of 10. Typical frost-free season: 144 days.JFMAMJJASONDLast frost ~May 13First frost ~Oct 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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 26September 20
50% (typical)May 13October 2
90% (likely)April 29October 15
Frost-free season (32°F, 50% chance)
144 days
Hard frost (28°F), last in spring, 50% chance after
April 30
Hard frost (28°F), first in fall, 50% chance before
October 14

The last 15 years (2006–2020 normals)

Typical last frost May 8 (5 days earlier than the 30-year normal), typical first fall frost October 5 (3 days later). Frost-free season 150 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 Worthington: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 26, 20% May 21, 30% May 18, 40% May 15, 50% May 13, 60% May 10, 70% May 6, 80% May 3, 90% April 29.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 26May 13Apr 29Fall at Worthington: chance of a frost before this dateFall, chance of a frost before the date: 10% September 20, 20% September 24, 30% September 28, 40% September 30, 50% October 2, 60% October 4, 70% October 6, 80% October 10, 90% October 15.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 20Oct 2Oct 15
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.

What these dates mean

September 20 is the cautious fall date in Worthington for finishing the harvest of tender crops; only a 10 % chance of a light frost has arrived earlier.

In spring the cautious date for setting out tender crops is May 26, when a light frost later than that day is only a 10 % risk, while an earlier May 13 is the 50 % date, the point at which a light frost is equally likely to have occurred or not. The 50 % light-frost dates of May 13 and October 2 give gardeners a clear median marker of even odds for a 32 °F frost, and the hard-frost 50 % dates of April 30 and October 14 serve the same purpose for a 28 °F event.

Because a hard frost at 28 °F can damage plants that survive a light frost at 32 °F, it is a more critical threshold for winter protection.

How to read the probabilities

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

  • Spring: "10% after May 26" 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 September 20" 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 Worthington, MANumbered nearest stations: 1 — Amherst, MA — 20 mi; 2 — Norfolk, CT — 32 mi; 3 — Hartford (Bradley Airport), CT — 33 mi; 4 — Bakersville, CT — 38 mi; 5 — near Fiskdale, MA — 45 mi.CTNYRI25 mi · 40 km1. Amherst, MA — 20 mi12. Norfolk, CT — 32 mi23. Hartford (Bradley Airport), CT — 33 mi34. Bakersville, CT — 38 mi45. near Fiskdale, MA — 45 mi5
  1. Amherst, MA 20 mi (32 km)
  2. Norfolk, CT 32 mi (52 km)
  3. Hartford (Bradley Airport), CT 33 mi (54 km)
  4. Bakersville, CT 38 mi (61 km)
  5. near Fiskdale, MA 45 mi (72 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: 42.3869, -72.9211.