U.S. Frost Dates by Weather Station

NOAA station USC00457015 · Washington

Frost Dates for Richland, WA

NOAA weather station Richland (USC00457015), Washington · elevation 373 ft (114 m) · hardiness zone 7b*

  • Lower-risk planting dateafter April 24only 1 spring in 10 still has a frost later
  • Typical last frostApril 650% chance of a frost after it
  • Typical first fall frostOctober 2450% chance of a frost before it
  • Frost-free season200 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season at Richland, WASpring: a frost after March 22 in 9 years out of 10, after April 6 in half of the years, after April 24 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 24 in half of the years, before November 8 in 9 years out of 10. Typical frost-free season: 200 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 6First frost ~Oct 24Frost season at Richland, WASpring: a frost after March 22 in 9 years out of 10, after April 6 in half of the years, after April 24 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 24 in half of the years, before November 8 in 9 years out of 10. Typical frost-free season: 200 days.JFMAMJJASONDLast frost ~Apr 6First frost ~Oct 24
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)April 24October 10
50% (typical)April 6October 24
90% (likely)March 22November 8
Frost-free season (32°F, 50% chance)
200 days
Hard frost (28°F), last in spring, 50% chance after
March 18
Hard frost (28°F), first in fall, 50% chance before
November 4

The last 15 years (2006–2020 normals)

Typical last frost April 4 (2 days earlier than the 30-year normal), typical first fall frost October 24. Frost-free season 201 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 Richland: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 24, 20% April 17, 30% April 13, 40% April 10, 50% April 6, 60% April 3, 70% March 31, 80% March 28, 90% March 22. Observed last spring frost in recent years: 2021 April 12, 2022 April 15, 2023 April 13, 2024 April 18, 2025 March 30, 2026 March 31.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 24Apr 6Mar 222021: April 122022: April 152023: April 132024: April 182025: March 302026: March 31Fall at Richland: chance of a frost before this dateFall, chance of a frost before the date: 10% October 10, 20% October 14, 30% October 18, 40% October 21, 50% October 24, 60% October 26, 70% October 30, 80% November 3, 90% November 8. Observed first fall frost in recent years: 2021 November 1, 2022 November 3, 2023 October 27, 2024 October 30, 2025 October 30.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 10Oct 24Nov 82021: November 12022: November 32023: October 272024: October 302025: October 30
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 12November 1
2022April 15November 3
2023April 13October 27
2024April 18October 30
2025March 30October 30
2026March 31season not over yet

What these dates mean

Setting out tender crops on March 22 in Richland carries a 90% chance of a light frost later, so it is a gamble. The 50% light-frost dates are April 6 in spring and October 24 in fall; at each of those dates there is an even chance of a frost occurring later (spring) or earlier (fall).

For a cautious approach, gardeners use the April 24 date, which has only a 10% chance of a later frost, and the October 10 date, which has only a 10% chance of an earlier frost. The hard-frost 50% dates are March 18 and November 4; a hard frost at 28 °F can damage plant tissue that survives a light frost at 32 °F, making it a more serious risk. The record spans 30 years of NOAA normals, so the percentages reflect three decades of observations.

How to read the probabilities

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

  • Spring: "10% after April 24" 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 10" 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 Richland, WANumbered nearest stations: 1 — Kennewick, WA — 10 mi; 2 — near Burbank, WA — 19 mi; 3 — Boardman, OR — 38 mi; 4 — Whitman Mission, WA — 43 mi; 5 — Pendleton, OR — 47 mi.25 mi · 40 km1. Kennewick, WA — 10 mi12. near Burbank, WA — 19 mi23. Boardman, OR — 38 mi34. Whitman Mission, WA — 43 mi45. Pendleton, OR — 47 mi5
  1. Kennewick, WA 10 mi (17 km)
  2. near Burbank, WA 19 mi (30 km)
  3. Boardman, OR 38 mi (61 km)
  4. Whitman Mission, WA 43 mi (68 km)
  5. Pendleton, OR 47 mi (76 km)

Sources

* Hardiness zone 7b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 46.3119, -119.2633.