U.S. Frost Dates by Weather Station

NOAA station USC00046136 · California

Frost Dates for Nevada City, CA

NOAA weather station Nevada City (USC00046136), California · elevation 2781 ft (848 m) · hardiness zone 9a*

  • Lower-risk planting dateafter May 7only 1 spring in 10 still has a frost later
  • Typical last frostApril 1450% chance of a frost after it
  • Typical first fall frostNovember 2050% chance of a frost before it
  • Frost-free season218 daystypical year, 32°F
  • Hardiness zone9acalculated*

The year at a glance

Frost season at Nevada City, CASpring: a frost after March 15 in 9 years out of 10, after April 14 in half of the years, after May 7 in 1 year out of 10. Fall: the first frost comes before October 23 in 1 year out of 10, before November 20 in half of the years, before December 12 in 9 years out of 10. Typical frost-free season: 218 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 14First frost ~Nov 20Frost season at Nevada City, CASpring: a frost after March 15 in 9 years out of 10, after April 14 in half of the years, after May 7 in 1 year out of 10. Fall: the first frost comes before October 23 in 1 year out of 10, before November 20 in half of the years, before December 12 in 9 years out of 10. Typical frost-free season: 218 days.JFMAMJJASONDLast frost ~Apr 14First frost ~Nov 20
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.Today

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 7October 23
50% (typical)April 14November 20
90% (likely)March 15December 12
Frost-free season (32°F, 50% chance)
218 days
Hard frost (28°F), last in spring, 50% chance after
March 17
Hard frost (28°F), first in fall, 50% chance before
December 8

The last 15 years (2006–2020 normals)

Typical last frost April 14 (same as the 30-year normal), typical first fall frost November 19 (1 day earlier). Frost-free season 214 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 Nevada City: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 7, 20% April 29, 30% April 23, 40% April 19, 50% April 14, 60% April 9, 70% April 4, 80% March 28, 90% March 15. Observed last spring frost in recent years: 2021 May 21, 2023 April 19, 2024 April 8, 2025 April 4, 2026 February 21.Spring: last frostChance of a frost after this date10%50%90%Mar 1Apr 1May 1May 7Apr 14Mar 152021: May 212023: April 192024: April 82025: April 42026: February 21Fall at Nevada City: chance of a frost before this dateFall, chance of a frost before the date: 10% October 23, 20% November 3, 30% November 10, 40% November 16, 50% November 20, 60% November 25, 70% November 30, 80% December 4, 90% December 12. Observed first fall frost in recent years: 2021 December 10, 2022 November 3, 2023 November 25, 2024 November 16, 2025 January 8.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Jan 1Oct 23Nov 20Dec 122021: December 102022: November 32023: November 252024: November 162025: January 8
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 21December 10
2022incomplete recordNovember 3
2023April 19November 25
2024April 8November 16
2025April 4January 8
2026February 21season not over yet

What these dates mean

Setting out tender crops on the early spring date, March 15, carries a 90 % chance of a light frost later, making it a gamble for growers in Nevada City.

The 50% date is April 14, meaning there is an even chance of a light frost on either side of that day, while the cautious spring date, May 7, has only a 10 % chance of a frost later and is the date a low-risk plan would use for tender crops. In the fall the cautious date is October 23, with a 10 % chance of a frost earlier, whereas the 50% date is November 20. The hard-frost 50% dates are March 17 in spring and December 8 in fall, and the record shows 218 days between the two 32 °F 50% dates over 28 years.

A hard frost at 28 °F can damage plants that survive a light frost at 32 °F because the colder temperature causes deeper tissue injury.

How to read the probabilities

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

  • Spring: "10% after May 7" 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 23" 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 Nevada City, CANumbered nearest stations: 1 — near Grass Valley, CA — 5 mi; 2 — Strawberry Valley, CA — 23 mi; 3 — Tahoe City, CA — 46 mi; 4 — Portola, CA — 48 mi; 5 — near Greenville, CA — 64 mi.NV25 mi · 40 km1. near Grass Valley, CA — 5 mi12. Strawberry Valley, CA — 23 mi23. Tahoe City, CA — 46 mi34. Portola, CA — 48 mi45. near Greenville, CA — 64 mi5
  1. near Grass Valley, CA 5 mi (7 km)
  2. Strawberry Valley, CA 23 mi (36 km)
  3. Tahoe City, CA 46 mi (74 km)
  4. Portola, CA 48 mi (77 km)
  5. near Greenville, CA 64 mi (103 km)

Sources

* Hardiness zone 9a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 39.2467, -121.0008.