Plainfield climate

Plainfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Indianapolis, 10.2 km from Plainfield, elevation 790 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Indianapolis. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around April 15 and the first fall freeze around October 26, a growing season of about 193 days.

Median at 36°F
last April 26, first October 17
Median at 32°F
last April 15, first October 26
Median at 28°F
last April 4, first November 5

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 12May 6May 3Apr 30Apr 26Apr 23Apr 20Apr 16Apr 11
32°FMay 2Apr 26Apr 21Apr 18Apr 15Apr 12Apr 9Apr 6Apr 2
28°FApr 21Apr 15Apr 10Apr 7Apr 4Apr 1Mar 29Mar 24Mar 18
24°FApr 8Apr 3Mar 31Mar 27Mar 24Mar 21Mar 17Mar 13Mar 7
20°FMar 28Mar 24Mar 19Mar 16Mar 13Mar 9Mar 6Mar 2Feb 24
16°FMar 19Mar 15Mar 10Mar 7Mar 3Feb 28Feb 23Feb 16Feb 8

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 5Oct 9Oct 12Oct 15Oct 17Oct 20Oct 22Oct 24Oct 28
32°FOct 13Oct 18Oct 21Oct 24Oct 26Oct 28Oct 30Nov 2Nov 7
28°FOct 24Oct 28Nov 1Nov 2Nov 5Nov 8Nov 12Nov 16Nov 21
24°FNov 2Nov 6Nov 10Nov 13Nov 17Nov 20Nov 24Nov 28Dec 4
20°FNov 10Nov 16Nov 20Nov 24Nov 28Dec 1Dec 4Dec 9Dec 16
16°FNov 17Nov 25Nov 29Dec 3Dec 6Dec 11Dec 16Dec 21Dec 26

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F191184179176171167163158151
32°F212205201197193189184178171
28°F236230225220215211207201195
24°F262253248244239235230225218
20°F285278272266260256251245238
16°F306297291286281276271265255

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
5,250
Cooling degree days, base 65°F
1,139
Growing degree days, base 40°F
6,104
Growing degree days, base 45°F
4,841
Growing degree days, base 50°F
3,715
Growing degree days, base 55°F
2,721
Growing degree days, base 60°F
1,861

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,13104
February91008
March702356
April35513178
May13186425
June14237673
July1336800
August2301764
September58142535
October31421218
November650148
December98308

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 10.2 km from Plainfield. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00093819 (Indianapolis). Public domain.