U.S. Frost Dates by Weather Station

NOAA station USC00040741 · California

Frost Dates for Big Bear Lake, CA

NOAA weather station Big Bear Lake (USC00040741), California · elevation 6753 ft (2058 m) · hardiness zone 7a*

  • Lower-risk planting dateafter June 9only 1 spring in 10 still has a frost later
  • Typical last frostMay 2750% chance of a frost after it
  • Typical first fall frostOctober 450% chance of a frost before it
  • Frost-free season131 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Big Bear Lake, CASpring: a frost after May 6 in 9 years out of 10, after May 27 in half of the years, after June 9 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 4 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 131 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 27First frost ~Oct 4Frost season at Big Bear Lake, CASpring: a frost after May 6 in 9 years out of 10, after May 27 in half of the years, after June 9 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 4 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 131 days.JFMAMJJASONDLast frost ~May 27First frost ~Oct 4
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)June 9September 21
50% (typical)May 27October 4
90% (likely)May 6October 20
Frost-free season (32°F, 50% chance)
131 days
Hard frost (28°F), last in spring, 50% chance after
May 4
Hard frost (28°F), first in fall, 50% chance before
October 20

The last 15 years (2006–2020 normals)

Typical last frost May 26 (1 day earlier than the 30-year normal), typical first fall frost October 2 (2 days earlier). Frost-free season 131 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 Big Bear Lake: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 9, 20% June 5, 30% June 2, 40% May 31, 50% May 27, 60% May 23, 70% May 18, 80% May 13, 90% May 6. Observed last spring frost in recent years: 2021 May 23, 2022 May 12, 2023 May 26, 2024 May 10, 2025 May 15, 2026 May 28.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 9May 27May 62021: May 232022: May 122023: May 262024: May 102025: May 152026: May 28Fall at Big Bear Lake: chance of a frost before this dateFall, chance of a frost before the date: 10% September 21, 20% September 26, 30% September 29, 40% October 1, 50% October 4, 60% October 7, 70% October 10, 80% October 14, 90% October 20. Observed first fall frost in recent years: 2021 October 1, 2022 October 23, 2023 September 28, 2024 September 17, 2025 October 12.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 21Oct 4Oct 202021: October 12022: October 232023: September 282024: September 172025: October 12
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 23October 1
2022May 12October 23
2023May 26September 28
2024May 10September 17
2025May 15October 12
2026May 28season not over yet

What these dates mean

The 131 days between the 32°F 50% dates—May 27 and October 4—contain the window for tender crops in Big Bear Lake. During this span growers can plan planting and harvesting around frost risk.

The median light-frost dates, May 27 and October 4, each hold a 50 % chance of a frost later (spring) or earlier (fall). For a cautious spring schedule the June 9 date carries only a 10 % chance of a frost later, while the May 6 date bears a 90 % chance and is a gamble. In the fall the September 21 date provides a 10 % chance of a frost earlier, whereas October 20 carries a 90 % chance and is risky for late tender crops.

A hard frost at 28 °F is more severe than a light frost, and its 50% dates—May 4 in spring and October 20 in fall—mark when the risk of damaging temperatures reaches even odds.

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 21" 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 Big Bear Lake, CANumbered nearest stations: 1 — near Barstow, CA — 43 mi; 2 — near Aguanga, CA — 60 mi; 3 — Sandberg, CA — 109 mi; 4 — Campo, CA — 115 mi; 5 — Pahrump, NV — 148 mi.CAAZNV100 mi · 161 km1. near Barstow, CA — 43 mi12. near Aguanga, CA — 60 mi23. Sandberg, CA — 109 mi34. Campo, CA — 115 mi45. Pahrump, NV — 148 mi5
  1. near Barstow, CA 43 mi (69 km)
  2. near Aguanga, CA 60 mi (96 km)
  3. Sandberg, CA 109 mi (175 km)
  4. Campo, CA 115 mi (184 km)
  5. Pahrump, NV 148 mi (238 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: 34.2431, -116.9169.