Louisville, KY Frost Dates: Last Spring and First Fall Frost

The last spring frost in Louisville, KY comes on April 6 in a typical year, and the first fall frost follows on November 1, leaving a frost-free season of 209 days.

Because half of all years do worse than the typical date, the dates that matter for tender plants are the late spring date, April 23, and the early fall date, October 21, each of which one year in ten fails to beat. Among the 100 cities covered here, whose median season is 229 days, Louisville ranks 68th for length and falls 20 days below the middle.

These dates come from the NOAA weather station Louisville WFO (ID USC00154958), 3.5 miles south of the Census Bureau's internal point for Louisville, at about 630 feet above sea level.

Last spring frost in Louisville

One year in ten has a freeze on or after April 23. In nine years out of ten there is still a freeze on or after March 23, and half of years see one on or after April 6.

Only 31 days separate the earliest and latest of these dates, a tighter run than most of the 100 cities here, so the typical date is a fairly dependable guide in Louisville.

When is the first frost in Louisville?

Expect the first freeze of fall by November 1 in a typical year. One year in ten brings it by October 21, and nine in ten have had it by November 15.

Fall frost keeps to a tight calendar in Louisville: 25 days from the 10% date to the 90% date, less than in most of the 100 cities here.

The growing season in Louisville

The season is somewhat shorter than the middle of these pages, so a seed packet's days to maturity deserve a second look. The record runs from 187 days in a short year through 209 days in a typical one to 229 days in a long one, a swing of 22 days below typical that is middling for these pages.

These figures are NOAA's own counts of freeze-free days across its simulated years, which is why they can differ a little from the days between the two typical dates. At Louisville WFO a night at or below 32°F turns up in 100% of years, which means these dates apply every winter.

28°F dates in Louisville

The two freezes sit close together here. The typical hard freeze reaches Louisville on November 11, 10 days after the first frost, and ends on March 26, 11 days ahead of the last. At the edges, a 28°F night on or after April 9 happens one spring in ten and one by November 1 one fall in ten; the nine-in-ten dates are March 9 and November 29.

What this means for planting in Louisville

The University of New Hampshire Extension sheet times each crop from the last frost. For Louisville's typical date, April 6, that means cabbage on March 9, lettuce from March 9 to March 16, seed potatoes from March 23 to March 30, and, once the frost is behind you, peppers on April 20 and beans on or after April 6. Peas have no frost-based date in the University of New Hampshire Extension sheet: they go in as soon as the soil thaws.

From the late date, April 23, every tender crop moves back 17 days; that buys protection against a spring only one year in ten brings.

Louisville's first frost leaves room for only 30 of the 34 fall crops, counting back NC State Extension's days to harvest and University of Georgia Extension's harvest allowance of 18 days; for the other 4 the last planting day falls before July. The slowest crop that still fits is Florence fennel, at 108 days, and it has to be planted by July 5 to beat the early date.

Worked example: a tomato plan for Louisville

Take tomatoes in Louisville. The University of New Hampshire Extension rule is to set transplants out one to two weeks after the last frost. From April 6, the typical date, that means April 13 to April 20; from April 23, the late date, it means April 30 to May 7, a delay of 17 days.

Seeds start six to eight weeks before the set-out day, so counting back from the first day of the late window gives March 5 to March 19 for sowing indoors.

Between the last set-out day and the early first frost on October 21 lie 167 days. Tomatoes need 75 to 85 days by NC State Extension's count, so the schedule has 82 days of slack even in an early-frost year.

About the Louisville WFO station

The station is 3.5 miles south of the Census Bureau's internal point for Louisville, near enough to be the city's reference record, though not in the same yard.

At about 630 feet, it ranks above 48 and below 51 of the 100 stations used for these pages. In NOAA's file the record is marked S, meaning standard.

No elevation is available for Louisville in the Census data we saved, so the station's height may or may not match your garden's. Compare nearby stations in the frost dates tool if it does not, and err toward the colder dates.

Nearby cities and their frost dates

Here is how Louisville, with a last frost on April 6 and a first frost on November 1, compares with the three nearest cities on these pages, the closest being Lexington, KY at 65 miles.

• Lexington, KY lies 65 miles east of Louisville. Typical last frost April 13, first frost October 28, 196 days between; spring frost lingers 7 days longer than in Louisville, and it has 13 days less without frost.
• Cincinnati, OH lies 91 miles north-east of Louisville. Typical last frost April 16, first frost October 25, 190 days between; its last frost comes 10 days after Louisville's, and the frost-free season is 19 days shorter than Louisville's.
• Indianapolis, IN (115 miles, north): its last frost comes 14 days after Louisville's, and the season runs 26 days shorter. Its typical dates are April 20 and October 21, with 183 days frost-free.

Take these dates further

To go beyond the crops above, use the spring planting planner and fall planting planner, both set to this station. The frost dates tool shows the full odds for Louisville, and the hardiness zone lookup gives the winter-cold zone for your ZIP code.

Looking for another city? The city frost dates index lists every page, grouped by state.

For Kentucky, the state planting pages copy the Extension calendar (University of Kentucky Cooperative Extension) crop by crop and region by region: tomatoes in Kentucky, peppers in Kentucky, cucumbers in Kentucky, summer squash in Kentucky, green beans in Kentucky. Set those windows beside the frost dates above.

Where these numbers come from

NOAA's U.S. Climate Normals for 1991–2020 (doi:10.25921/4ek7-fk11) supply every frost date here, unchanged from the station's record, and NOAA's documentation defines the probabilities. The Census Bureau's 2024 Gazetteer places Louisville on the map, and its Vintage 2024 estimates, 640,796 people here, decide which cities get a page.

University of New Hampshire Extension, NC State Extension and University of Georgia Extension supply the planting rules; this page only counts them from the station's dates. See how we source every figure for the checks behind them.

NOAA's dates say how often frost has come, not when it will. Check the forecast before planting and keep a cover on hand.