U.S. Frost Dates by Weather Station

NOAA station USC00374266 · Rhode Island

Frost Dates for Kingston, RI

NOAA weather station Kingston (USC00374266), Rhode Island · elevation 117 ft (36 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 16only 1 spring in 10 still has a frost later
  • Typical last frostMay 350% chance of a frost after it
  • Typical first fall frostOctober 850% chance of a frost before it
  • Frost-free season159 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Kingston, RISpring: a frost after April 21 in 9 years out of 10, after May 3 in half of the years, after May 16 in 1 year out of 10. Fall: the first frost comes before September 30 in 1 year out of 10, before October 8 in half of the years, before October 23 in 9 years out of 10. Typical frost-free season: 159 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 3First frost ~Oct 8Frost season at Kingston, RISpring: a frost after April 21 in 9 years out of 10, after May 3 in half of the years, after May 16 in 1 year out of 10. Fall: the first frost comes before September 30 in 1 year out of 10, before October 8 in half of the years, before October 23 in 9 years out of 10. Typical frost-free season: 159 days.JFMAMJJASONDLast frost ~May 3First frost ~Oct 8
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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 16September 30
50% (typical)May 3October 8
90% (likely)April 21October 23
Frost-free season (32°F, 50% chance)
159 days
Hard frost (28°F), last in spring, 50% chance after
April 20
Hard frost (28°F), first in fall, 50% chance before
October 20

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 14 (6 days later). Frost-free season 165 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 Kingston: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 16, 20% May 11, 30% May 8, 40% May 5, 50% May 3, 60% April 30, 70% April 28, 80% April 25, 90% April 21. Observed last spring frost in recent years: 2021 April 24, 2022 May 1, 2023 May 18, 2024 April 27, 2025 April 21, 2026 May 4.Spring: last frostChance of a frost after this date10%50%90%May 1May 16May 3Apr 212021: April 242022: May 12023: May 182024: April 272025: April 212026: May 4Fall at Kingston: chance of a frost before this dateFall, chance of a frost before the date: 10% September 30, 20% October 2, 30% October 4, 40% October 6, 50% October 8, 60% October 11, 70% October 14, 80% October 18, 90% October 23. Observed first fall frost in recent years: 2021 November 2, 2022 October 9, 2023 November 2, 2024 October 11, 2025 October 10.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 30Oct 8Oct 232021: November 22022: October 92023: November 22024: October 112025: 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 24November 2
2022May 1October 9
2023May 18November 2
2024April 27October 11
2025April 21October 10
2026May 4season not over yet

What these dates mean

The cautious fall date in Kingston for finishing the harvest is September 30. That date carries only a 10 % chance that a light frost has arrived earlier, so planting tender crops after it reduces risk. In spring the cautious date for setting out tender crops is May 16, when there is a 10 % chance of a later frost; planting before that is a gamble.

The 50 % light-frost dates are May 3 in spring and October 8 in fall; each represents an even odds point and is not itself a frost date. The 50 % hard-frost dates are April 20 and October 20, indicating where a 28 °F freeze is equally likely to have occurred or not.

A hard frost at 28 °F can injure plants that survive a 32 °F light frost, making it the more critical temperature 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 16" 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 30" 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 Kingston, RINumbered nearest stations: 1 — near Providence, RI — 17 mi; 2 — North Foster, RI — 27 mi; 3 — near Norwich, CT — 27 mi; 4 — Rochester, MA — 38 mi; 5 — Storrs, CT — 41 mi.MACTRI25 mi · 40 km1. near Providence, RI — 17 mi12. North Foster, RI — 27 mi23. near Norwich, CT — 27 mi34. Rochester, MA — 38 mi45. Storrs, CT — 41 mi5
  1. near Providence, RI 17 mi (27 km)
  2. North Foster, RI 27 mi (44 km)
  3. near Norwich, CT 27 mi (44 km)
  4. Rochester, MA 38 mi (61 km)
  5. Storrs, CT 41 mi (66 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: 41.4903, -71.5431.