Average dates derived from 1991-2020 NOAA NCEI 30-year climate normals at KSDF (Louisville) — NCEI publishes normals only for first-order NWS stations, and KSDF is the closest. Our live forecast uses KFTK (Fort Knox/Godman, ~12 mi) where available since it's much closer to the river. River bottoms run 1-2 weeks later than these averages; ridgetops 1-2 weeks earlier.
24°F — Killing Freeze
234 growing days
Last spring: March 24 · First fall: November 13
Kills most semi-hardy plants. Garlic, kale, and overwintering brassicas survive. Soil starts freezing.
28°F — Hard Freeze
214 growing days
Last spring: April 3 · First fall: November 3
Kills warm-season vegetables outright. Lettuce and kale survive; everything mature in the garden is finished.
32°F — Light Frost
193 growing days
Last spring: April 14 · First fall: October 24
Kills tender annuals (basil, beans, tomatoes). Most flowers handle it; row covers buy a season-edge week.
Source: NOAA NCEI Climate Normals 1991-2020. Public-domain federal data.