U.S. Frost Dates by Weather Station

NOAA station USC00042574 · California

Frost Dates near Dunsmuir, CA

NOAA weather station Dunsmuir Trtmt PL (USC00042574), California · elevation 2169 ft (661 m) · hardiness zone 8b*

Dunsmuir is the nearest town to the station (1.8 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 May 12only 1 spring in 10 still has a frost later
  • Typical last frostApril 2350% chance of a frost after it
  • Typical first fall frostOctober 2750% chance of a frost before it
  • Frost-free season185 daystypical year, 32°F
  • Hardiness zone8bcalculated*

The year at a glance

Frost season near Dunsmuir, CASpring: a frost after April 5 in 9 years out of 10, after April 23 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 9 in 1 year out of 10, before October 27 in half of the years, before November 10 in 9 years out of 10. Typical frost-free season: 185 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 23First frost ~Oct 27Frost season near Dunsmuir, CASpring: a frost after April 5 in 9 years out of 10, after April 23 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 9 in 1 year out of 10, before October 27 in half of the years, before November 10 in 9 years out of 10. Typical frost-free season: 185 days.JFMAMJJASONDLast frost ~Apr 23First frost ~Oct 27
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)May 12October 9
50% (typical)April 23October 27
90% (likely)April 5November 10
Frost-free season (32°F, 50% chance)
185 days
Hard frost (28°F), last in spring, 50% chance after
March 31
Hard frost (28°F), first in fall, 50% chance before
November 12

The last 15 years (2006–2020 normals)

Typical last frost April 26 (3 days later than the 30-year normal), typical first fall frost October 29 (2 days later). Frost-free season 185 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 Dunsmuir: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 12, 20% May 5, 30% May 1, 40% April 27, 50% April 23, 60% April 20, 70% April 17, 80% April 12, 90% April 5. Observed last spring frost in recent years: 2021 April 27, 2022 May 12, 2023 April 20, 2024 May 6, 2025 April 5, 2026 April 24.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 12Apr 23Apr 52021: April 272022: May 122023: April 202024: May 62025: April 52026: April 24Fall near Dunsmuir: chance of a frost before this dateFall, chance of a frost before the date: 10% October 9, 20% October 16, 30% October 20, 40% October 24, 50% October 27, 60% October 30, 70% November 1, 80% November 5, 90% November 10. Observed first fall frost in recent years: 2021 October 8, 2022 October 24, 2023 October 26, 2025 November 22.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 9Oct 27Nov 102021: October 82022: October 242023: October 262025: November 22
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 27October 8
2022May 12October 24
2023April 20October 26
2024May 6incomplete record
2025April 5November 22
2026April 24season not over yet

What these dates mean

May 12 is the cautious spring date for the Dunsmuir area, reflecting only a 10 % chance that a light frost will occur later. That level of risk lets a gardener plan to set out tender crops with reasonable confidence.

April 23 is the 50% date for light frost, meaning odds are even that a frost could be later or earlier; planting before April 5 carries a 90 % chance of a frost and is a gamble. In the fall, October 9 is the cautious date, offering only a 10 % chance that a light frost has already arrived, which guides the latest time to finish harvesting tender crops. The 50% fall date is October 27, where the odds of a frost are balanced, while November 10 carries a 90 % chance of a frost and is risky for late crops.

The 50% hard-frost dates are March 31 in spring and November 12 in fall; a hard frost at 28 °F can damage plants that survive a 32 °F light frost, making it a more critical threshold for growers.

How to read the probabilities

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

  • Spring: "10% after May 12" 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 9" 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 Dunsmuir, CANumbered nearest stations: 1 — near Lewiston, CA — 41 mi; 2 — Redding, CA — 46 mi; 3 — Chester, CA — 82 mi; 4 — near Medford, OR — 88 mi; 5 — near Greenville, CA — 94 mi.ORNV50 mi · 80 km1. near Lewiston, CA — 41 mi12. Redding, CA — 46 mi23. Chester, CA — 82 mi34. near Medford, OR — 88 mi45. near Greenville, CA — 94 mi5
  1. near Lewiston, CA 41 mi (67 km)
  2. Redding, CA 46 mi (74 km)
  3. Chester, CA 82 mi (131 km)
  4. near Medford, OR 88 mi (142 km)
  5. near Greenville, CA 94 mi (151 km)

Sources

* Hardiness zone 8b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 41.1831, -122.2817.