Frost Dates
Frost Dates · Arizona

Frost dates for Scottsdale, Arizona

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

Typical last spring freeze (32°F)
January 27
median date, 1991–2020
Typical first fall freeze (32°F)
December 21
median date, 1991–2020
Typical frost-free season
328 days
between the median dates

In a typical year, the last spring freeze around Scottsdale comes near January 27 and the first fall freeze near December 21. One year in ten, a freeze still arrives after March 5 in spring — and one year in ten, the first fall freeze has already landed by November 28. NCEI's own growing-season statistic (days between freezes, percentiled per year) puts the median at 330 days.

JFMAMJJASONDJanuary 27December 21
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 Pinnacle Peak, AZ (USC00026603), 3.0 mi from the city's census reference point, elev. 2,565 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)January 17February 26March 30November 19December 7December 24
32°F — freezingDecember 23January 27March 5November 28December 21January 24
28°F — hard freezeDecember 14January 6February 8December 6January 1February 2

Measured at Pinnacle Peak, AZ (USC00026603), 3.0 mi from the city's census reference point, elev. 2,565 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 5November 28268 days
Typical (median freeze dates)January 27December 21328 days
Gambler's (9-in-10 freeze risk at each end)December 23January 24365 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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