Indianapolis, IN Frost Dates: Last Spring and First Fall Frost

Frost leaves Indianapolis on April 20 and comes back on October 21 when the odds are even, a window of 183 days for tender plants.

Dates at even odds leave half of all years unprotected. The safer pair for Indianapolis is May 5 in spring, which only one year in ten passes, and October 7 in fall, which one year in ten arrives before. Indianapolis's season is 46 days shorter than the 229 days median across the 100 cities on these pages, so it ranks 81st for season length.

These dates come from the NOAA weather station Indianapolis SE Side (ID USC00124272), 5.9 miles south-east of the Census Bureau's internal point for Indianapolis, at about 850 feet above sea level.

When is the last frost in Indianapolis?

Frost is still possible on April 6 in nine springs out of ten and on April 20 in five; only one spring in ten sees a freeze as late as May 5.

The early and late dates sit just 29 days apart, narrower than for most cities on these pages. Spring in Indianapolis rarely surprises by much.

Indianapolis's first fall frost, by chance

A first freeze on or before October 7 happens one fall in ten. By October 21 half of years have had one, and by November 3 nine years in ten have.

The early and late fall dates are only 27 days apart, a narrow band next to most cities here, so the first freeze keeps close to its schedule in Indianapolis.

Indianapolis's frost-free season

That is shorter than most places on these pages, so days to maturity on the seed packet matter more than usual. Seasons here barely vary: the typical year gives 183 days and a short one still gives 163 days, only 20 days less, a steadier record than most cities on 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 Indianapolis SE Side a night at or below 32°F turns up in 100% of years, which means these dates apply every winter.

Hard freeze dates for Indianapolis

NOAA's even-odds hard freeze dates for Indianapolis are November 1 in fall and April 7 in spring, 11 days and 13 days from the matching 32°F dates. One spring in ten still has a 28°F night on or after April 23, and one fall in ten sees the first by October 20.

Planting dates for Indianapolis, counted from the frost dates

In Indianapolis the University of New Hampshire Extension count lands like this, measured from the typical last frost on April 20: lettuce from March 23 to March 30, cabbage on March 23, seed potatoes from April 6 to April 13, then peppers on May 4 and beans from April 20. The University of New Hampshire Extension sheet gives peas no frost count at all; sow them as soon as the soil thaws.

The late date comes 15 days after the typical one; choose it for plants you cannot cover.

Of the 34 crops in the fall planner, 28 still have a July-or-later last planting day in Indianapolis once NC State Extension's days to harvest and University of Georgia Extension's harvest allowance of 18 days are counted back from frost. The other 6 do not. The slowest crop that still fits is broccoli, which needs 98 days before the early first frost and so must be in by July 1.

Worked example: a tomato plan for Indianapolis

A gardener in Indianapolis who follows University of New Hampshire Extension sets tomato transplants out one to two weeks after the last frost: April 27 to May 4 from the typical date of April 20, or May 12 to May 19 from the late date of May 5, 15 days later.

Seeds start six to eight weeks before the set-out day, so counting back from the first day of the late window gives March 17 to March 31 for sowing indoors.

That leaves 141 days against 75 to 85 days for the plants to reach harvest, so even the late schedule fits in an early-frost year with 56 days to spare.

Where Indianapolis's numbers are measured

The station is 5.9 miles south-east of the Census Bureau's internal point for Indianapolis, near enough to be the city's reference record, though not in the same yard.

NOAA lists it at about 850 feet, higher than 65 and lower than 34 of the 100 stations in this set. In NOAA's file the record is marked R, meaning representative.

Because the Census file has no elevation for Indianapolis, we cannot say how far your yard is above or below this station. When yours is clearly higher or lower, open the nearby stations in the frost dates tool and favor the colder one.

Indianapolis compared with nearby cities

Here is how Indianapolis, with a last frost on April 20 and a first frost on October 21, compares with the three nearest cities on these pages, the closest being Cincinnati, OH at 98 miles.

• Cincinnati, OH lies 98 miles south-east of Indianapolis. Typical last frost April 16, first frost October 25, 190 days between; its last frost comes 4 days before Indianapolis's, and frost-free days differ from Indianapolis's by less than a week.
• Fort Wayne, IN lies 105 miles north-east of Indianapolis. Typical last frost April 24, first frost October 21, 178 days between; spring frost lingers 4 days longer than in Indianapolis, and frost-free days differ from Indianapolis's by less than a week.
• Louisville, KY, 115 miles to the south: last frost April 6, first frost November 1, 209 days frost-free; the last frost is 14 days earlier than in Indianapolis, and the frost-free season is 26 days longer than Indianapolis's.

Take these dates further

Start with the spring planting planner for the whole crop list counted from these dates, and the fall planting planner for the last planting days. The frost dates tool shows every level of risk at this station, and the hardiness zone lookup covers winter survival for shrubs and perennials.

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

Where these numbers come from

The frost and freeze dates are NOAA's U.S. Climate Normals for 1991–2020 (doi:10.25921/4ek7-fk11), copied from the station's own record without adjustment; NOAA's documentation defines each probability. The city and its internal point come from the Census Bureau's 2024 Gazetteer of places, and the ranking by size from the Census Bureau's Vintage 2024 city and town population estimates, which put Indianapolis at 891,484 people.

Planting dates here are those rules from University of New Hampshire Extension, NC State Extension and University of Georgia Extension, applied to this station's frost dates and nothing else. Our methodology describes the tests behind every number.

These dates describe odds over many years, not next week's weather. Look at the forecast before you plant, and keep a sheet or row cover ready for a night that does not follow the odds.