USDA Hardiness Zone 6b
Frost Dates for 46131 — Franklin, Indiana
NOAA 1991–2020 normals from Franklin Wwtp, IN (720 ft), 1 miles southeast.
Updated
In Franklin, the last spring frost (32°F) is around April 20 in half of years and has passed by May 7 in nine years out of ten. The first fall frost comes around October 19, as early as October 7 one year in ten, leaving a typical freeze-free season of 180 days (NOAA, Franklin Wwtp, IN).
- Last spring frost
- April 20
- First fall frost
- October 19
- Growing season
- 180 days
- Hardiness zone
- 6b
50% probability
50% probability
freeze-free, 50%
-5 to 0°F (-20.6 to -17.8°C) coldest night
- First snow
- December 19
- Last snow
- March 3
- Winters with snow
- 100%
- Snow per year
- 16.9"
median, 1991–2020
median, 1991–2020
20 of 20 observed
NOAA normal
Frost risk by date in Franklin
Half of springs at Franklin Wwtp, IN see their last 32°F night by April 20; only one in ten is past it by April 7, and one in ten still has one after May 7. Planting tender crops after April 27 leaves a 30% risk of a frost on them, after May 1 20%, and after May 7 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 66% of the 125 Indiana stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 19 in half of years, as early as October 7 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 10 days later, around October 29; in spring the one-in-ten date for 28°F is April 24, 13 days before the 32°F one. The freeze-free season lasts 180 days in a typical year, shorter than at 54% of the 125 Indiana stations; it reaches 199 days one year in ten and falls short of 160 one year in ten. On average 117 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 11 days longer, to about May 1, and return around October 10. Severe cold of 16°F or below comes every winter, usually between December 2 and March 10.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 18 | Apr 22 | Apr 25 | Apr 29 | May 1 | May 4 | May 7 | May 11 | May 16 |
| 32°F | Apr 7 | Apr 11 | Apr 15 | Apr 18 | Apr 20 | Apr 23 | Apr 27 | May 1 | May 7 |
| 28°F | Mar 25 | Mar 31 | Apr 3 | Apr 5 | Apr 8 | Apr 12 | Apr 15 | Apr 19 | Apr 24 |
| 24°F | Mar 13 | Mar 19 | Mar 23 | Mar 26 | Mar 30 | Apr 1 | Apr 3 | Apr 7 | Apr 12 |
| 20°F | Mar 3 | Mar 8 | Mar 12 | Mar 15 | Mar 18 | Mar 21 | Mar 24 | Mar 29 | Apr 1 |
| 16°F | Feb 20 | Feb 28 | Mar 3 | Mar 6 | Mar 10 | Mar 12 | Mar 16 | Mar 19 | Mar 24 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 29 | Oct 3 | Oct 5 | Oct 8 | Oct 10 | Oct 12 | Oct 14 | Oct 17 | Oct 23 |
| 32°F | Oct 7 | Oct 11 | Oct 15 | Oct 17 | Oct 19 | Oct 22 | Oct 24 | Oct 27 | Nov 1 |
| 28°F | Oct 17 | Oct 21 | Oct 24 | Oct 26 | Oct 29 | Oct 31 | Nov 2 | Nov 6 | Nov 12 |
| 24°F | Oct 26 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 11 | Nov 14 | Nov 18 | Nov 25 |
| 20°F | Nov 4 | Nov 8 | Nov 13 | Nov 16 | Nov 20 | Nov 24 | Nov 29 | Dec 3 | Dec 9 |
| 16°F | Nov 12 | Nov 18 | Nov 24 | Nov 29 | Dec 2 | Dec 5 | Dec 10 | Dec 16 | Dec 23 |
Freeze probabilities 1991–2020 at Franklin Wwtp, IN, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 46131 →Compare Franklin with another place →
Frost risk through the year in Franklin
In Franklin, the spring curve drops under 10% on May 7 and the fall curve passes 10% on October 7, 153 days later; that gap is longer than at 50% of the 125 Indiana stations with frost dates. The spring risk falls from 90% to 10% over 30 days (April 7 to May 7) and the fall risk climbs from 10% to 90% over 25 days (October 7 to November 1): both ends of the season vary about as much. At Shelbyville Sewage Plt, IN, 14 miles east, the same gap runs from May 3 to October 9, 6 days longer.
| Planted on | Another 32°F night | 28°F night |
|---|---|---|
| Apr 6 | over 90% | 57% |
| Apr 13 | 75% | 37% |
| Apr 2050% date | 50% | 18% |
| Apr 27 | 30% | under 10% |
| May 4 | 15% | under 10% |
| May 11 | under 10% | under 10% |
Weather by month in Franklin
July is the warmest month at Franklin Wwtp, IN, averaging 84°F by day and 64°F at night; January is the coldest at 35°F and 18°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 21% of years.
Warmth for growing adds up to 3,303 growing degree days a year (base 50°F), fewer than at 54% of the 125 Indiana stations. 36% of them (1,186) have built up by the end of June, and July adds the most, 744. Precipitation totals 45.4 inches a year, most in May (5.3") and least in February (2.5"); May to September bring 46% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 35 | 18 | 3.0 | 100% | 26 | 2 |
| Feb | 40 | 20 | 2.5 | 100% | 24 | 4 |
| Mar | 51 | 29 | 3.7 | 100% | 18 | 38 |
| Apr | 63 | 40 | 4.9 | 97% | 5 | 134 |
| May | 73 | 51 | 5.3 | 21% | <1 | 376 |
| Jun | 81 | 61 | 5.1 | 0% | 0 | 631 |
| Jul | 84 | 64 | 4.2 | 0% | 0 | 744 |
| Aug | 83 | 61 | 3.3 | 0% | 0 | 684 |
| Sep | 78 | 54 | 3.2 | 2% | 0 | 483 |
| Oct | 66 | 41 | 3.3 | 89% | 4 | 174 |
| Nov | 52 | 31 | 3.5 | 100% | 16 | 29 |
| Dec | 40 | 23 | 3.4 | 100% | 24 | 5 |
Monthly normals 1991–2020 at Franklin Wwtp, IN (720 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Shelbyville Sewage Plt, IN, 14 miles east of Franklin, has a last frost 3 days earlier (April 17), a first frost 3 days later (October 22), a season 7 days longer.
When it snows in Franklin, Indiana
The first measurable snow (0.1 inch or more) in Franklin usually arrives around December 19, and the last of the season around March 3. Those are the middle dates across the winters of 1991–2020 at Franklin Wwtp, IN, 1.1 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 48 days after the last snow.
Planting calendar for 46131
| When | What to do |
|---|---|
| February 9 – February 23 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 23 – March 9 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 23 – April 6 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 20 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 27 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 5 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 19 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 46131 is 1 mile from Franklin Wwtp, IN, which stands at 720 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 46131 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.