U.S. Frost Dates by Weather Station

NOAA station USC00041700 · California

Frost Dates for Chester, CA

NOAA weather station Chester (USC00041700), California · elevation 4530 ft (1381 m) · hardiness zone 7a*

  • Lower-risk planting dateafter June 13only 1 spring in 10 still has a frost later
  • Typical last frostMay 2850% chance of a frost after it
  • Typical first fall frostSeptember 2850% chance of a frost before it
  • Frost-free season124 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Chester, CASpring: a frost after May 7 in 9 years out of 10, after May 28 in half of the years, after June 13 in 1 year out of 10. Fall: the first frost comes before September 12 in 1 year out of 10, before September 28 in half of the years, before October 14 in 9 years out of 10. Typical frost-free season: 124 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 28First frost ~Sep 28Frost season at Chester, CASpring: a frost after May 7 in 9 years out of 10, after May 28 in half of the years, after June 13 in 1 year out of 10. Fall: the first frost comes before September 12 in 1 year out of 10, before September 28 in half of the years, before October 14 in 9 years out of 10. Typical frost-free season: 124 days.JFMAMJJASONDLast frost ~May 28First frost ~Sep 28
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 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 13September 12
50% (typical)May 28September 28
90% (likely)May 7October 14
Frost-free season (32°F, 50% chance)
124 days
Hard frost (28°F), last in spring, 50% chance after
May 2
Hard frost (28°F), first in fall, 50% chance before
October 18

The last 15 years (2006–2020 normals)

Typical last frost May 28 (same as the 30-year normal), typical first fall frost October 1 (3 days later). Frost-free season 128 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 Chester: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 13, 20% June 8, 30% June 4, 40% May 31, 50% May 28, 60% May 22, 70% May 18, 80% May 14, 90% May 7. Observed last spring frost in recent years: 2021 June 9, 2022 May 13, 2024 June 2.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 13May 28May 72021: June 92022: May 132024: June 2Fall at Chester: chance of a frost before this dateFall, chance of a frost before the date: 10% September 12, 20% September 17, 30% September 21, 40% September 25, 50% September 28, 60% October 1, 70% October 5, 80% October 8, 90% October 14. Observed first fall frost in recent years: 2022 October 23, 2024 November 10.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Nov 1Sep 12Sep 28Oct 142022: October 232024: November 10
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
2021June 9incomplete record
2022May 13October 23
2023no dataincomplete record
2024June 2November 10
2025incomplete recordincomplete record
2026no dataseason not over yet

What these dates mean

June 13 is the cautious spring date for light frost in Chester; with only a 10 % chance of a frost after that day, a gardener can plan to set out tender crops with minimal risk. The 50 % date of May 28 marks the point where there is an even chance of a light frost occurring later, while the hard-frost 50 % date of May 2 indicates a 50 % chance of temperatures dropping to 28 °F.

September 12 serves as the cautious fall date, giving a 10 % chance that a light frost has arrived earlier, so harvesting tender crops can be completed with confidence. The median light-frost date of September 28 represents a 50 % chance of frost earlier, and the hard-frost 50 % date of October 18 signals a 50 % chance of temperatures reaching 28 °F.

Because a hard frost at 28 °F can damage plant tissue that survives a light frost at 32 °F, the hard-frost dates are especially important for protecting sensitive 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 13" 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 12" 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 Chester, CANumbered nearest stations: 1 — near Greenville, CA — 12 mi; 2 — Strawberry Valley, CA — 52 mi; 3 — Portola, CA — 53 mi; 4 — Redding, CA — 58 mi; 5 — Nevada City, CA — 74 mi.CANV25 mi · 40 km1. near Greenville, CA — 12 mi12. Strawberry Valley, CA — 52 mi23. Portola, CA — 53 mi34. Redding, CA — 58 mi45. Nevada City, CA — 74 mi5
  1. near Greenville, CA 12 mi (20 km)
  2. Strawberry Valley, CA 52 mi (83 km)
  3. Portola, CA 53 mi (86 km)
  4. Redding, CA 58 mi (93 km)
  5. Nevada City, CA 74 mi (119 km)

Sources

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

Station coordinates: 40.3033, -121.2422.