Frost Dates
Frost Dates · California

Frost dates for Lancaster, California

California · first & last freeze, from NOAA 1991–2020 climate normals

Typical last spring freeze (32°F)
April 3
median date, 1991–2020
Typical first fall freeze (32°F)
November 1
median date, 1991–2020
Typical frost-free season
212 days
between the median dates

In a typical year, the last spring freeze around Lancaster comes near April 3 and the first fall freeze near November 1. One year in ten, a freeze still arrives after April 23 in spring — and one year in ten, the first fall freeze has already landed by October 17. NCEI's own growing-season statistic (days between freezes, percentiled per year) puts the median at 211 days.

JFMAMJJASONDApril 3November 1
The year at a glance: blue bands span the 9-in-10 to 1-in-10 range where the last spring / first fall 32°F freeze lands; the green band is the typical frost-free window between the median dates. Measured at Lancaster Wm J Fox Fld, CA (USW00003159), 3.9 mi from the city's census reference point, elev. 2,338 ft. NOAA/NCEI 1991–2020 normals.

Freeze-date probabilities, three thresholds

ThresholdLast spring — 9 in 10 years past byLast spring — typical (median)Last spring — 1 in 10 years later thanFirst fall — 1 in 10 years byFirst fall — typical (median)First fall — 9 in 10 years by
36°F — near-freezing (frost can occur)March 31April 19May 5October 7October 22November 3
32°F — freezingMarch 8April 3April 23October 17November 1November 14
28°F — hard freezeFebruary 14March 8April 7October 28November 10November 26

Measured at Lancaster Wm J Fox Fld, CA (USW00003159), 3.9 mi from the city's census reference point, elev. 2,338 ft. NOAA/NCEI 1991–2020 normals. Read each date column as odds over the 30-year record — e.g. "9 in 10 years past by" means only one spring in ten saw a later freeze than that date.

Frost-free windows (computed)

Window (32°F ends)OpensClosesLength
Cautious (1-in-10 freeze risk at each end)April 23October 17177 days
Typical (median freeze dates)April 3November 1212 days
Gambler's (9-in-10 freeze risk at each end)March 8November 14251 days

Pure arithmetic on the freeze-date percentiles above — the "cautious" window opens on the date only 1 year in 10 still sees a later spring freeze, and closes on the date by which only 1 year in 10 has already frozen.

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