U.S. Frost Dates by Weather Station

NOAA station USC00454338 · Washington

Frost Dates for Lacrosse, WA

NOAA weather station Lacrosse (USC00454338), Washington · elevation 1476 ft (450 m) · hardiness zone 6b*

  • Lower-risk planting dateafter June 1only 1 spring in 10 still has a frost later
  • Typical last frostMay 1350% chance of a frost after it
  • Typical first fall frostSeptember 2650% chance of a frost before it
  • Frost-free season133 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Lacrosse, WASpring: a frost after April 28 in 9 years out of 10, after May 13 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 8 in 1 year out of 10, before September 26 in half of the years, before October 11 in 9 years out of 10. Typical frost-free season: 133 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 13First frost ~Sep 26Frost season at Lacrosse, WASpring: a frost after April 28 in 9 years out of 10, after May 13 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 8 in 1 year out of 10, before September 26 in half of the years, before October 11 in 9 years out of 10. Typical frost-free season: 133 days.JFMAMJJASONDLast frost ~May 13First frost ~Sep 26
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)June 1September 8
50% (typical)May 13September 26
90% (likely)April 28October 11
Frost-free season (32°F, 50% chance)
133 days
Hard frost (28°F), last in spring, 50% chance after
April 29
Hard frost (28°F), first in fall, 50% chance before
October 7

The last 15 years (2006–2020 normals)

Typical last frost May 11 (2 days earlier than the 30-year normal), typical first fall frost September 27 (1 day later). Frost-free season 136 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 Lacrosse: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 1, 20% May 25, 30% May 19, 40% May 16, 50% May 13, 60% May 10, 70% May 6, 80% May 3, 90% April 28. Observed last spring frost in recent years: 2021 May 23.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 1May 13Apr 282021: May 23Fall at Lacrosse: chance of a frost before this dateFall, chance of a frost before the date: 10% September 8, 20% September 14, 30% September 19, 40% September 23, 50% September 26, 60% September 29, 70% October 2, 80% October 5, 90% October 11.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 8Sep 26Oct 11
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 23no data
2022no datano data
2023no datano data
2024no datano data
2025no datano data
2026no dataseason not over yet

What these dates mean

Setting out tender crops on April 28 in Lacrosse carries a 90% chance of a light frost, making it a gamble for gardeners.

The cautious spring date for tender crops is June 1, when only a 10% chance of a light frost remains, and the cautious fall date is September 8, also with a 10% chance of an earlier frost. The 50% date is May 13 in spring and September 26 in fall; each marks the point at which a light frost is equally likely to occur later or earlier. The 50% hard-frost dates are April 29 and October 7, indicating when a 28 °F freeze is as likely as not.

A hard frost at 28 °F can damage plants more severely than a light 32 °F frost. The interval between the two 32 °F 50% dates spans 133 days over the 27-year record.

How to read the probabilities

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

  • Spring: "10% after June 1" 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 8" 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 Lacrosse, WANumbered nearest stations: 1 — St. John, WA — 24 mi; 2 — Ritzville, WA — 31 mi; 3 — Pullman, WA — 33 mi; 4 — Dayton, WA — 35 mi; 5 — near Lewiston, ID — 51 mi.WAID25 mi · 40 km1. St. John, WA — 24 mi12. Ritzville, WA — 31 mi23. Pullman, WA — 33 mi34. Dayton, WA — 35 mi45. near Lewiston, ID — 51 mi5
  1. St. John, WA 24 mi (38 km)
  2. Ritzville, WA 31 mi (50 km)
  3. Pullman, WA 33 mi (53 km)
  4. Dayton, WA 35 mi (56 km)
  5. near Lewiston, ID 51 mi (83 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: 46.8167, -117.8831.