Frost Dates
Frost Dates · Washington

Frost dates for Tacoma, Washington

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

Typical last spring freeze (32°F)
March 8
median date, 1991–2020
Typical first fall freeze (32°F)
November 14
median date, 1991–2020
Typical frost-free season
251 days
between the median dates

In a typical year, the last spring freeze around Tacoma comes near March 8 and the first fall freeze near November 14. One year in ten, a freeze still arrives after March 31 in spring — and one year in ten, the first fall freeze has already landed by October 30. NCEI's own growing-season statistic (days between freezes, percentiled per year) puts the median at 250 days.

JFMAMJJASONDMarch 8November 14
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 Tacoma #1, WA (USC00458278), 2.2 mi from the city's census reference point, elev. 25 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 13April 2April 24October 16October 31November 15
32°F — freezingFebruary 15March 8March 31October 30November 14December 2
28°F — hard freezeDecember 29February 11March 4November 8December 1January 1

Measured at Tacoma #1, WA (USC00458278), 2.2 mi from the city's census reference point, elev. 25 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 31October 30213 days
Typical (median freeze dates)March 8November 14251 days
Gambler's (9-in-10 freeze risk at each end)February 15December 2290 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.

About this city's numbers

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