U.S. Frost Dates by Weather Station

NOAA station USW00014740 · Connecticut

Frost Dates for Hartford (Bradley Airport), CT

NOAA weather station Hartford Bradley International Airport (USW00014740), Connecticut · elevation 190 ft (58 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 6only 1 spring in 10 still has a frost later
  • Typical last frostApril 2150% chance of a frost after it
  • Typical first fall frostOctober 1650% chance of a frost before it
  • Frost-free season177 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Hartford (Bradley Airport), CTSpring: a frost after April 8 in 9 years out of 10, after April 21 in half of the years, after May 6 in 1 year out of 10. Fall: the first frost comes before October 3 in 1 year out of 10, before October 16 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 177 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 21First frost ~Oct 16Frost season at Hartford (Bradley Airport), CTSpring: a frost after April 8 in 9 years out of 10, after April 21 in half of the years, after May 6 in 1 year out of 10. Fall: the first frost comes before October 3 in 1 year out of 10, before October 16 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 177 days.JFMAMJJASONDLast frost ~Apr 21First frost ~Oct 16
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 6October 3
50% (typical)April 21October 16
90% (likely)April 8November 2
Frost-free season (32°F, 50% chance)
177 days
Hard frost (28°F), last in spring, 50% chance after
April 7
Hard frost (28°F), first in fall, 50% chance before
October 29

The last 15 years (2006–2020 normals)

Typical last frost April 20 (1 day earlier than the 30-year normal), typical first fall frost October 22 (6 days later). Frost-free season 183 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 Hartford (Bradley Airport): chance of a frost after this dateSpring, chance of a frost after the date: 10% May 6, 20% May 1, 30% April 27, 40% April 24, 50% April 21, 60% April 19, 70% April 16, 80% April 12, 90% April 8. Observed last spring frost in recent years: 2021 April 22, 2022 April 21, 2023 May 18, 2024 April 23, 2025 April 18, 2026 April 25.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 6Apr 21Apr 82021: April 222022: April 212023: May 182024: April 232025: April 182026: April 25Fall at Hartford (Bradley Airport): chance of a frost before this dateFall, chance of a frost before the date: 10% October 3, 20% October 7, 30% October 10, 40% October 13, 50% October 16, 60% October 19, 70% October 23, 80% October 27, 90% November 2. Observed first fall frost in recent years: 2021 November 4, 2022 October 21, 2023 November 1, 2024 October 17, 2025 October 10.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 3Oct 16Nov 22021: November 42022: October 212023: November 12024: October 172025: 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 22November 4
2022April 21October 21
2023May 18November 1
2024April 23October 17
2025April 18October 10
2026April 25season not over yet

What these dates mean

The cautious spring date of May 6, when there is only a 10 % chance of a light frost later, lets a gardener plan to set out tender crops. The 50 % date of April 21 marks the point at which a light frost is equally likely to occur later, providing a statistical midpoint for scheduling.

In the fall, the cautious date of October 3, with a 10 % chance of a light frost earlier, indicates when tender crops should be finished harvesting. The 50 % date of October 16 is the median point where a light frost is equally likely to have arrived earlier.

Hard-frost median dates are April 7 in spring and October 29 in fall; a hard frost at 28 °F can damage plants that survive a light frost, making it a more critical threshold.

How to read the probabilities

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

  • Spring: "10% after May 6" 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 Hartford (Bradley Airport), CTNumbered nearest stations: 1 — Hartford (Brainard Field), CT — 14 mi; 2 — Bakersville, CT — 18 mi; 3 — Storrs, CT — 25 mi; 4 — Norfolk, CT — 28 mi; 5 — near Fiskdale, MA — 31 mi.MANYRI25 mi · 40 km1. Hartford (Brainard Field), CT — 14 mi12. Bakersville, CT — 18 mi23. Storrs, CT — 25 mi34. Norfolk, CT — 28 mi45. near Fiskdale, MA — 31 mi5
  1. Hartford (Brainard Field), CT 14 mi (23 km)
  2. Bakersville, CT 18 mi (29 km)
  3. Storrs, CT 25 mi (41 km)
  4. Norfolk, CT 28 mi (45 km)
  5. near Fiskdale, MA 31 mi (50 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: 41.9381, -72.6825.