U.S. Frost Dates by Weather Station

NOAA station USC00105275 · Idaho

Frost Dates near Paris, ID

NOAA weather station Lifton Pumping Station (USC00105275), Idaho · elevation 5935 ft (1809 m) · hardiness zone 5a*

Paris is the nearest town to the station (8.5 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter June 5only 1 spring in 10 still has a frost later
  • Typical last frostMay 1950% chance of a frost after it
  • Typical first fall frostSeptember 2150% chance of a frost before it
  • Frost-free season123 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season near Paris, IDSpring: a frost after May 3 in 9 years out of 10, after May 19 in half of the years, after June 5 in 1 year out of 10. Fall: the first frost comes before September 5 in 1 year out of 10, before September 21 in half of the years, before October 5 in 9 years out of 10. Typical frost-free season: 123 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 19First frost ~Sep 21Frost season near Paris, IDSpring: a frost after May 3 in 9 years out of 10, after May 19 in half of the years, after June 5 in 1 year out of 10. Fall: the first frost comes before September 5 in 1 year out of 10, before September 21 in half of the years, before October 5 in 9 years out of 10. Typical frost-free season: 123 days.JFMAMJJASONDLast frost ~May 19First frost ~Sep 21
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 5September 5
50% (typical)May 19September 21
90% (likely)May 3October 5
Frost-free season (32°F, 50% chance)
123 days
Hard frost (28°F), last in spring, 50% chance after
May 3
Hard frost (28°F), first in fall, 50% chance before
October 3

The last 15 years (2006–2020 normals)

Typical last frost May 18 (1 day earlier than the 30-year normal), typical first fall frost September 24 (3 days later). Frost-free season 126 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 near Paris: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 5, 20% May 31, 30% May 27, 40% May 23, 50% May 19, 60% May 15, 70% May 12, 80% May 8, 90% May 3. Observed last spring frost in recent years: 2021 May 12, 2022 June 16, 2023 May 9, 2024 May 25, 2025 May 20, 2026 June 11.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 5May 19May 32021: May 122022: June 162023: May 92024: May 252025: May 202026: June 11Fall near Paris: chance of a frost before this dateFall, chance of a frost before the date: 10% September 5, 20% September 10, 30% September 15, 40% September 18, 50% September 21, 60% September 24, 70% September 27, 80% October 1, 90% October 5. Observed first fall frost in recent years: 2021 September 21, 2022 October 13, 2023 October 16, 2024 October 19.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 5Sep 21Oct 52021: September 212022: October 132023: October 162024: October 19
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
2021May 12September 21
2022June 16October 13
2023May 9October 16
2024May 25October 19
2025May 20incomplete record
2026June 11season not over yet

What these dates mean

The 123 days between the 32°F 50% dates—May 19 and September 21—enclose the interval when light frosts are less likely, providing the main growing window for the Paris area.

May 19 is the 50% date, indicating a 50% chance of a frost later than this date; the cautious spring date for setting out tender crops is June 5, which carries only a 10% chance of a later frost, while the gamble date of May 3 carries a 90% chance. September 21 is the 50% date, indicating a 50% chance of a frost earlier than this date; the cautious fall date to finish harvesting tender crops is September 5, with a 10% chance of an earlier frost, and the gamble date of October 5 carries a 90% chance. The hard-frost 50% dates are May 3 and October 3.

A hard frost at 28 °F can injure plant tissue that would usually survive the milder 32 °F light frost.

How to read the probabilities

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

  • Spring: "10% after June 5" 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 5" 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 Paris, IDNumbered nearest stations: 1 — Bern, ID — 15 mi; 2 — Laketown, UT — 21 mi; 3 — Preston, ID — 29 mi; 4 — Richmond, UT — 30 mi; 5 — near Logan, UT — 36 mi.IDWYUT25 mi · 40 km1. Bern, ID — 15 mi12. Laketown, UT — 21 mi23. Preston, ID — 29 mi34. Richmond, UT — 30 mi45. near Logan, UT — 36 mi5
  1. Bern, ID 15 mi (24 km)
  2. Laketown, UT 21 mi (33 km)
  3. Preston, ID 29 mi (47 km)
  4. Richmond, UT 30 mi (48 km)
  5. near Logan, UT 36 mi (58 km)

Sources

* Hardiness zone 5a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 42.1231, -111.3133.