Indianapolis, Indiana Frost Dates, Growing Season & Hardiness Zone

When is the last frost in Indianapolis?

In half of years, the last 32°F night has passed by Apr 20. In 1 year out of 10, one still comes after May 5. The last 36°F night (frost possible on plants) typically comes later, around Apr 30, and the last 28°F hard freeze earlier, around Apr 7.

Indianapolis has a long late-frost tail: 15 days separate the typical date (Apr 20) from the safer 1-in-10 date (May 5). If tender plants go out early, be ready to protect them 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 30, 10 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 Indianapolis?

Before Apr 20 the odds of another 32°F night are better than even; after May 5 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 Indianapolis?

The typical first fall freeze (32°F) comes by Oct 21, but 1 year in 10 it shows up as early as Oct 7. Cold 36°F nights (frost possible on plants) typically start around Oct 11, and the first hard freeze (28°F) typically comes around Nov 1.

For fall crops, count back from Oct 21, or from Oct 7 to be safe. Our planting calendar does the math for each crop.

How long is Indianapolis's growing season?

In a typical year, Indianapolis gets 183 days between the last and first 32°F nights. About 1 year in 10, the season is shorter than 163 days.

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

Growing degree days measure the heat available for crops to grow. The station averages 3,384 a year (base 50°F).

How does Indianapolis's season compare?

Nationwide, across the 56 cities with frost dates on this site, the typical frost-free season here outlasts the one in 22 of them and falls short of the one in 32.

Growing degree days (base 50°F)

Annual normal: 3,384 GDD (NOAA flag R, 21 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 Indianapolis? (USDA 2023)

On the 2023 USDA map, Indianapolis is zone 6a–6b (-10 to 0°F average coldest winter night). On the 2012 map, most of the city was 6a. Of the 38 city ZIPs listed in both tables, 22 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 Indianapolis's frost dates?

No. Zones describe only how cold the coldest winter night gets on average. They don't tell you when frost starts or stops. The frost dates for Indianapolis come from NOAA's 1991–2020 frost probabilities, which the 2023 zone map left untouched. Choose winter-hardy perennials by zone, and schedule planting by frost dates.

Why do Indianapolis frost dates differ between websites?

If you've seen Apr 26 listed as Indianapolis's last frost date, that's the 30%-risk date: about 3 years in 10 still get a 32°F night after it. We lead with Apr 20, the 50% (median) date.

The 'safer' date, May 5, is the 10%-risk date. A 32°F night after it happens in only about 1 year in 10.

Apr 30 is the 50% date for a 36°F night (frost possible on plants), not a 32°F freeze. Sites that treat 36°F as the danger line show later dates.

The choice of weather station matters too. The 9 stations within 25 miles of the city center that pass our quality rules give typical (50%) last 32°F frost dates from Apr 12 to Apr 21; see the table below.

Which weather station is this based on?

Station

Indianapolis SE Side (NOAA USC00124272, COOP)

Distance

5.9 mi SE of the city center

Elevation

845 ft; city center 719 ft (USGS), difference +126 ft

Record

NOAA completeness flag R, 23 of 30 years (1991–2020)

Confidence

High (rule)

Confidence: High. The station is close (5.9 miles from the city center), its elevation differs by just 126 ft, and its frost statistics meet our completeness rule (NOAA flag R, 23 of 30 years).

Note: NOAA rates this station's frost statistics 'R' (representative). That means they use 23 of the 30 years in 1991–2020, with missing months filled in from surrounding stations. For comparison, the nearest station with a full 'S' (standard) record, Indianapolis (8.6 mi away), has a typical last frost of Apr 15.

Indianapolis planting dates at a glance

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

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

Frost dates near Indianapolis

All Indiana cities

Frequently asked questions

What is the average last frost date in Indianapolis?

The typical (median, 50%) last 32°F night in Indianapolis is Apr 20, based on NOAA 1991–2020 normals at Indianapolis SE Side. For a safer target, use May 5; after that, only about 1 year in 10 still has a freeze.

When is the first frost in Indianapolis?

Typically by Oct 21 for the first 32°F night, though about 1 year in 10 it comes as early as Oct 7. The first 36°F night (frost possible on plants) typically shows up around Oct 11.

What growing zone is Indianapolis, Indiana?

Indianapolis is in USDA hardiness zone 6a–6b on the current 2023 map. On the older 2012 map, most of the city was 6a, so older references may list that zone.

Is it too early to plant in Indianapolis?

Before Apr 20, yes, for anything frost-tender. Until then, the odds of another 32°F night are better than even. The risk falls from 50% to 10% between Apr 20 and May 5. Peas, lettuce and other cool-season crops can go in weeks earlier; the planting calendar has dates.

What temperature is a killing frost?

It depends on the crop. Tender plants such as tomatoes are killed by a light frost, which CSU Extension describes as 28–32°F; below 28°F is a heavy frost. We show NOAA odds for 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 Indianapolis, the first 36°F night (frost possible on plants) typically comes around Oct 11, before the first 32°F night (Oct 21).

Download & sources

• Add Indianapolis 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 USC00124272); 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.