Louisville, Kentucky Frost Dates, Growing Season & Hardiness Zone

When is the last frost in Louisville?

In half of years, the last 32°F night has passed by Apr 6. In 1 year out of 10, one still comes after Apr 23. The last 36°F night (frost possible on plants) typically comes later, around Apr 19, and the last 28°F hard freeze earlier, around Mar 26.

Frost risk in Louisville drags on well past the typical date. The safer 1-in-10 date (Apr 23) is 17 days later than the typical Apr 6, so protect tender plants set out early on cold nights.

Cool nights hang on after the last freeze: the typical last 36°F night (frost possible on plants in low spots) is around Apr 19, 13 days later than the typical last 32°F night. Frost can form on leaves on clear, calm nights even with the thermometer above freezing.

Is it too early to plant in Louisville?

Before Apr 6 the odds of another 32°F night are better than even; after Apr 23 they are about 1 in 10 or less.

Today's risk is computed in your browser from the same NOAA probability table, shown as the range between the two nearest NOAA probability levels.

When is the first frost in Louisville?

By Nov 1, half of years have had their first 32°F night. In 1 year out of 10, it comes as early as Oct 21. In a typical year, look for the first 36°F night (frost possible on plants) around Oct 23 and the first 28°F hard freeze around Nov 11.

For fall crops, count back from Nov 1, or from Oct 21 to be safe. Our planting calendar does the math for each crop.

How long is Louisville's growing season?

Louisville's frost-free season (32°F) typically runs 209 days. In about 1 year out of 10, it's shorter than 187 days.

A season this long fits most warm-season vegetables planted on time. Long-season crops do best when started from transplants.

The station averages 4,292 growing degree days (base 50°F) a year. That number measures how much heat crops have to grow on.

How does Louisville's season compare?

Compared with the 56 U.S. cities with frost dates on this site, this typical frost-free season is longer than in 27 and shorter than in 28.

Growing degree days (base 50°F)

Annual normal: 4,292 GDD (NOAA flag S, 24 years). Running total by the end of each month (sum of NOAA daily GDD normals, so the year-end total can differ slightly from the annual normal):

What growing zone is Louisville? (USDA 2023)

The 2023 USDA map puts Louisville in zone 6b–7a (-5 to 5°F average coldest winter night). On the 2012 map, most of the city was 6b. Comparing ZIPs listed in both tables, 26 of 31 moved up half a zone.

Zones: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 2026-10-08. Shown as published in the ZIP tables; this page does not show a zone map. Not the official USDA Plant Hardiness Zone Map (official map: planthardiness.ars.usda.gov).

Does the new zone change Louisville's frost dates?

No. A hardiness zone reflects only the average coldest winter temperature, not the timing of spring or fall frost. Louisville's frost dates come from NOAA's 1991–2020 frost probabilities, and the 2023 zone map didn't change them. Pick perennials that survive winter by zone; time your planting by frost dates.

Why do Louisville frost dates differ between websites?

You may see Apr 13 given as Louisville's last frost date. That's the 30%-risk date, meaning about 3 years in 10 still have a 32°F night after it. Our headline date is Apr 6, the 50% (median) date.

Apr 23 is the 10%-risk, or 'safer', date. Only about 1 year in 10 has a 32°F night after it.

You may also see Apr 19. That's the 50% date for a 36°F night (frost possible on plants) rather than a 32°F freeze, so sites using 36°F as their cutoff list later dates.

The choice of weather station matters too. The 8 stations within 25 miles of the city center that pass our quality rules give typical (50%) last 32°F frost dates from Mar 31 to May 1; see the table below.

Which weather station is this based on?

Station

Louisville (NOAA USC00154958, COOP)

Distance

3.5 mi S of the city center

Elevation

632 ft; city center 520 ft (USGS), difference +112 ft

Record

NOAA completeness flag S, 24 of 30 years (1991–2020)

Confidence

High (rule)

Confidence: High. The station is close (3.5 miles from the city center), its elevation differs by just 112 ft, and its frost statistics meet our completeness rule (NOAA flag S, 24 of 30 years).

Louisville planting dates at a glance

Balanced dates use the 30%-risk last-frost date as the anchor. The Louisville planting calendar has typical and safe dates, fall planting and a month-by-month list for 26 vegetables.

When to plant tomatoes in Louisville · Fall planting dates for Louisville

Frost dates near Louisville

All Kentucky cities

Frequently asked questions

What is the average last frost date in Louisville?

The typical (median, 50%) last 32°F night in Louisville is Apr 6, based on NOAA 1991–2020 normals at Louisville. For a safer target, use Apr 23; after that, only about 1 year in 10 still has a freeze.

When is the first frost in Louisville?

Typically by Nov 1 for the first 32°F night, though about 1 year in 10 it comes as early as Oct 21. The first 36°F night (frost possible on plants) typically shows up around Oct 23.

What growing zone is Louisville, Kentucky? Is Louisville zone 6 or 7?

On the current 2023 USDA map, Louisville is in hardiness zone 6b–7a, part of zone 6–7. Older references may still say 'zone 6' because most of the city was 6b on the 2012 map.

Is it too early to plant in Louisville?

For frost-tender plants, yes if it's before Apr 6: until then, the odds of another 32°F night are better than even. Between Apr 6 and Apr 23, the risk falls from 50% to 10%. Cool-season crops like peas and lettuce can go in weeks earlier; see the planting calendar.

What temperature is a killing frost?

A light frost is enough to kill tender crops such as tomatoes. CSU Extension describes 28–32°F as a light frost and anything below 28°F as a heavy frost. We report NOAA odds at three thresholds: 36°F (frost possible on plants), 32°F (freeze, our headline) and 28°F (hard freeze).

Is first frost the same as first freeze?

Not quite. A freeze is when the air reaches 32°F. Frost is ice that forms on surfaces, and on calm, clear nights it can form with the air a few degrees above freezing. So in Louisville, the first 36°F night (frost possible on plants) typically comes around Oct 23, before the first 32°F night (Nov 1).

Download & sources

• Add Louisville frost & planting dates to your calendar (.ics, 2027)
• Printable planting calendar (PDF)
• How these numbers are calculated

Data: NOAA NCEI U.S. Climate Normals 1991–2020 (annual/seasonal and daily normals, station USC00154958); USDA Plant Hardiness Zone ZIP tables 2023 and 2012 by the PRISM Group, Oregon State University; Census 2020 ZIP/place relationship file; USGS elevation. Long-term odds, not a forecast. Figures and sentences are generated from these data by fixed rules; see the methodology. Last updated 2026-10-08.