U.S. Frost Dates by Weather Station

NOAA station USC00041497 · California

Frost Dates near Greenville, CA

NOAA weather station Canyon Dam (USC00041497), California · elevation 4560 ft (1390 m) · hardiness zone 7b*

Greenville is the nearest town to the station (7.6 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 9only 1 spring in 10 still has a frost later
  • Typical last frostMay 1850% chance of a frost after it
  • Typical first fall frostOctober 850% chance of a frost before it
  • Frost-free season143 daystypical year, 32°F
  • Hardiness zone7bcalculated*

The year at a glance

Frost season near Greenville, CASpring: a frost after April 30 in 9 years out of 10, after May 18 in half of the years, after June 9 in 1 year out of 10. Fall: the first frost comes before September 24 in 1 year out of 10, before October 8 in half of the years, before October 24 in 9 years out of 10. Typical frost-free season: 143 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 18First frost ~Oct 8Frost season near Greenville, CASpring: a frost after April 30 in 9 years out of 10, after May 18 in half of the years, after June 9 in 1 year out of 10. Fall: the first frost comes before September 24 in 1 year out of 10, before October 8 in half of the years, before October 24 in 9 years out of 10. Typical frost-free season: 143 days.JFMAMJJASONDLast frost ~May 18First 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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 9September 24
50% (typical)May 18October 8
90% (likely)April 30October 24
Frost-free season (32°F, 50% chance)
143 days
Hard frost (28°F), last in spring, 50% chance after
April 26
Hard frost (28°F), first in fall, 50% chance before
October 26

The last 15 years (2006–2020 normals)

Typical last frost May 21 (3 days later than the 30-year normal), typical first fall frost October 8. Frost-free season 143 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 Greenville: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 9, 20% June 3, 30% May 29, 40% May 23, 50% May 18, 60% May 13, 70% May 9, 80% May 4, 90% April 30.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 9May 18Apr 30Fall near Greenville: chance of a frost before this dateFall, chance of a frost before the date: 10% September 24, 20% September 29, 30% October 3, 40% October 6, 50% October 8, 60% October 11, 70% October 15, 80% October 19, 90% October 24.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 24Oct 8Oct 24
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.

What these dates mean

September 24 marks the cautious fall date for the Greenville area, giving only a 10% chance that a light frost has arrived and signalling the last reliable day to finish harvesting tender crops.

For light-frost risk, the median 50% dates are May 18 in spring and October 8 in fall; a 50% chance of a frost later than May 18 or earlier than October 8 defines the middle of the risk window. The hard-frost median dates are April 26 and October 26, indicating the point at which a 28 °F frost is equally likely to have occurred or not. A cautious planting plan therefore uses June 9 as the spring date with only a 10% chance of a later frost, and the already-mentioned September 24 for the fall.

Hard frost at 28 °F can damage plants that survive a light 32 °F frost, making it a more critical concern for tender crops.

How to read the probabilities

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

  • Spring: "10% after June 9" 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 24" 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 Greenville, CANumbered nearest stations: 1 — Chester, CA — 12 mi; 2 — Portola, CA — 41 mi; 3 — Strawberry Valley, CA — 42 mi; 4 — Nevada City, CA — 64 mi; 5 — near Grass Valley, CA — 67 mi.CANV25 mi · 40 km1. Chester, CA — 12 mi12. Portola, CA — 41 mi23. Strawberry Valley, CA — 42 mi34. Nevada City, CA — 64 mi45. near Grass Valley, CA — 67 mi5
  1. Chester, CA 12 mi (20 km)
  2. Portola, CA 41 mi (66 km)
  3. Strawberry Valley, CA 42 mi (68 km)
  4. Nevada City, CA 64 mi (103 km)
  5. near Grass Valley, CA 67 mi (107 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: 40.1706, -121.0886.