Frost Dates
Frost Dates · California

Frost dates for Vista, California

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

Typical last spring freeze (32°F)
January 30
median date, 1991–2020
Typical first fall freeze (32°F)
January 7
median date, 1991–2020
Typical frost-free season
342 days
between the median dates

In a typical year, the last spring freeze around Vista comes near January 30 and the first fall freeze near January 7. One year in ten, a freeze still arrives after March 16 in spring — and one year in ten, the first fall freeze has already landed by December 14. NCEI's own growing-season statistic (days between freezes, percentiled per year) puts the median at 365 days.

JFMAMJJASONDJanuary 30January 7
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 Vista, CA (USC00049378), 3.2 mi from the city's census reference point, elev. 430 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)December 27February 16April 6December 4December 25February 9
32°F — freezingDecember 20January 30March 16December 14January 7March 14
28°F — hard freezeDecember 14December 30March 16December 13December 30March 16

Measured at Vista, CA (USC00049378), 3.2 mi from the city's census reference point, elev. 430 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)March 16December 14273 days
Typical (median freeze dates)January 30January 7342 days
Gambler's (9-in-10 freeze risk at each end)December 20March 14365 days (effectively year-round at this risk level)

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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