Frost Dates
Frost Dates · Tennessee

Frost dates for Knoxville, Tennessee

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

Typical last spring freeze (32°F)
April 11
median date, 1991–2020
Typical first fall freeze (32°F)
October 28
median date, 1991–2020
Typical frost-free season
200 days
between the median dates

In a typical year, the last spring freeze around Knoxville comes near April 11 and the first fall freeze near October 28. One year in ten, a freeze still arrives after April 29 in spring — and one year in ten, the first fall freeze has already landed by October 13. NCEI's own growing-season statistic (days between freezes, percentiled per year) puts the median at 198 days.

JFMAMJJASONDApril 11October 28
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 Knoxville Exp Stn, TN (USC00404946), 5.0 mi from the city's census reference point, elev. 830 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)April 9April 24May 10October 7October 19November 1
32°F — freezingMarch 26April 11April 29October 13October 28November 9
28°F — hard freezeMarch 13March 31April 16October 24November 6November 20

Measured at Knoxville Exp Stn, TN (USC00404946), 5.0 mi from the city's census reference point, elev. 830 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 29October 13167 days
Typical (median freeze dates)April 11October 28200 days
Gambler's (9-in-10 freeze risk at each end)March 26November 9228 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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