U.S. Frost Dates by Weather Station

NOAA station USC00196783 · Massachusetts

Frost Dates for Reading, MA

NOAA weather station Reading (USC00196783), Massachusetts · elevation 110 ft (34 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 8only 1 spring in 10 still has a frost later
  • Typical last frostApril 2550% chance of a frost after it
  • Typical first fall frostOctober 1750% chance of a frost before it
  • Frost-free season174 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Reading, MASpring: a frost after April 13 in 9 years out of 10, after April 25 in half of the years, after May 8 in 1 year out of 10. Fall: the first frost comes before October 3 in 1 year out of 10, before October 17 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 174 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 25First frost ~Oct 17Frost season at Reading, MASpring: a frost after April 13 in 9 years out of 10, after April 25 in half of the years, after May 8 in 1 year out of 10. Fall: the first frost comes before October 3 in 1 year out of 10, before October 17 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 174 days.JFMAMJJASONDLast frost ~Apr 25First frost ~Oct 17
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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 8October 3
50% (typical)April 25October 17
90% (likely)April 13November 1
Frost-free season (32°F, 50% chance)
174 days
Hard frost (28°F), last in spring, 50% chance after
April 11
Hard frost (28°F), first in fall, 50% chance before
October 30

The last 15 years (2006–2020 normals)

Typical last frost April 20 (5 days earlier than the 30-year normal), typical first fall frost October 23 (6 days later). Frost-free season 185 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 Reading: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 8, 20% May 4, 30% May 1, 40% April 28, 50% April 25, 60% April 23, 70% April 21, 80% April 18, 90% April 13.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 8Apr 25Apr 13Fall at Reading: chance of a frost before this dateFall, chance of a frost before the date: 10% October 3, 20% October 7, 30% October 11, 40% October 14, 50% October 17, 60% October 20, 70% October 23, 80% October 28, 90% November 1.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 3Oct 17Nov 1
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

May 8 is the cautious spring date, indicating a ten-percent chance that a light frost will occur later and allowing gardeners to set out tender crops with relatively low risk. The median light-frost dates are April 25 in spring and October 17 in fall; each marks the point at which a light frost is equally likely. October 3 is the cautious fall date, showing a ten-percent chance that a light frost has already arrived and giving gardeners a reliable endpoint for harvesting tender crops. The probabilities are derived from a 27-year record at the Reading station.

Hard-frost median dates are April 11 and October 30; hard frost at 28 °F can damage plants more severely than a light frost at 32 °F because lower temperatures cause greater tissue injury. The interval between the two 32°F 50% dates is 174 days, framing the central period of frost risk.

How to read the probabilities

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

  • Spring: "10% after May 8" 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 3" 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 Reading, MANumbered nearest stations: 1 — Middleton, MA — 7 mi; 2 — Lawrence, MA — 12 mi; 3 — near Boston, MA — 13 mi; 4 — Marblehead, MA — 13 mi; 5 — Lowell, MA — 15 mi.MANHVT25 mi · 40 km1. Middleton, MA — 7 mi12. Lawrence, MA — 12 mi23. near Boston, MA — 13 mi34. Marblehead, MA — 13 mi45. Lowell, MA — 15 mi5
  1. Middleton, MA 7 mi (12 km)
  2. Lawrence, MA 12 mi (20 km)
  3. near Boston, MA 13 mi (20 km)
  4. Marblehead, MA 13 mi (22 km)
  5. Lowell, MA 15 mi (23 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: 42.5239, -71.125.