U.S. Frost Dates by Weather Station

NOAA station USC00065445 · Connecticut

Frost Dates for Norfolk, CT

NOAA weather station Norfolk 2 SW (USC00065445), Connecticut · elevation 1340 ft (408 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 17only 1 spring in 10 still has a frost later
  • Typical last frostMay 350% chance of a frost after it
  • Typical first fall frostOctober 1150% chance of a frost before it
  • Frost-free season161 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Norfolk, CTSpring: a frost after April 21 in 9 years out of 10, after May 3 in half of the years, after May 17 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 11 in half of the years, before October 28 in 9 years out of 10. Typical frost-free season: 161 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 3First frost ~Oct 11Frost season at Norfolk, CTSpring: a frost after April 21 in 9 years out of 10, after May 3 in half of the years, after May 17 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 11 in half of the years, before October 28 in 9 years out of 10. Typical frost-free season: 161 days.JFMAMJJASONDLast frost ~May 3First frost ~Oct 11
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)May 17October 1
50% (typical)May 3October 11
90% (likely)April 21October 28
Frost-free season (32°F, 50% chance)
161 days
Hard frost (28°F), last in spring, 50% chance after
April 20
Hard frost (28°F), first in fall, 50% chance before
October 25

The last 15 years (2006–2020 normals)

Typical last frost April 30 (3 days earlier than the 30-year normal), typical first fall frost October 19 (8 days later). Frost-free season 170 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 Norfolk: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 17, 20% May 13, 30% May 9, 40% May 6, 50% May 3, 60% May 1, 70% April 29, 80% April 25, 90% April 21. Observed last spring frost in recent years: 2021 April 27, 2022 May 1, 2023 May 18, 2024 April 26, 2025 April 21, 2026 May 3.Spring: last frostChance of a frost after this date10%50%90%May 1May 17May 3Apr 212021: April 272022: May 12023: May 182024: April 262025: April 212026: May 3Fall at Norfolk: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 3, 30% October 6, 40% October 9, 50% October 11, 60% October 14, 70% October 18, 80% October 22, 90% October 28. Observed first fall frost in recent years: 2021 October 29, 2022 October 19, 2023 October 24, 2024 October 15, 2025 October 10.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 11Oct 282021: October 292022: October 192023: October 242024: October 152025: October 10
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 27October 29
2022May 1October 19
2023May 18October 24
2024April 26October 15
2025April 21October 10
2026May 3season not over yet

What these dates mean

October 1 marks the cautious fall date for finishing the harvest in Norfolk, as there is only a 10 % chance that a light frost has arrived by then.

For light frost, the 50 % dates are May 3 in spring and October 11 in fall; these dates represent even odds of a frost occurring later (spring) or earlier (fall) but are not frost dates themselves. The hard-frost 50 % dates are April 20 and October 25, indicating the median point for a 28 °F event.

A cautious plan for tender crops uses the May 17 light-frost date in spring, which carries a 10 % chance of a later frost, and the October 1 date in fall, which carries a 10 % chance of an earlier frost. A hard frost at 28 °F matters more than a light frost at 32 °F because the lower temperature can damage plants that would survive the milder frost.

How to read the probabilities

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

  • Spring: "10% after May 17" 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 1" 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 Norfolk, CTNumbered nearest stations: 1 — Bakersville, CT — 14 mi; 2 — Hartford (Bradley Airport), CT — 28 mi; 3 — Worthington, MA — 32 mi; 4 — Hartford (Brainard Field), CT — 34 mi; 5 — Amherst, MA — 45 mi.NYMARINHVT25 mi · 40 km1. Bakersville, CT — 14 mi12. Hartford (Bradley Airport), CT — 28 mi23. Worthington, MA — 32 mi34. Hartford (Brainard Field), CT — 34 mi45. Amherst, MA — 45 mi5
  1. Bakersville, CT 14 mi (23 km)
  2. Hartford (Bradley Airport), CT 28 mi (45 km)
  3. Worthington, MA 32 mi (52 km)
  4. Hartford (Brainard Field), CT 34 mi (54 km)
  5. Amherst, MA 45 mi (73 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: 41.9725, -73.2208.