Brownsburg climate

Brownsburg Frost Dates and Growing Season

NOAA 1991-2020 normals for Indianapolis Eagle Creek AP, 9 km from Brownsburg, elevation 823 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Indianapolis Eagle Creek AP. 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 12 and the first fall freeze around October 29, a growing season of about 198 days.

Median at 36°F
last April 23, first October 18
Median at 32°F
last April 12, first October 29
Median at 28°F
last April 1, first November 6

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 9May 3Apr 30Apr 26Apr 23Apr 20Apr 18Apr 14Apr 9
32°FApr 29Apr 22Apr 19Apr 16Apr 12Apr 9Apr 5Apr 2Mar 30
28°FApr 17Apr 10Apr 6Apr 3Apr 1Mar 29Mar 26Mar 22Mar 16
24°FApr 5Mar 31Mar 28Mar 24Mar 21Mar 17Mar 14Mar 10Mar 5
20°FMar 27Mar 21Mar 17Mar 14Mar 11Mar 8Mar 4Feb 28Feb 22
16°FMar 16Mar 11Mar 7Mar 3Mar 1Feb 26Feb 21Feb 15Feb 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 7Oct 11Oct 14Oct 16Oct 18Oct 21Oct 23Oct 26Oct 29
32°FOct 16Oct 21Oct 24Oct 26Oct 29Oct 31Nov 2Nov 5Nov 10
28°FOct 27Oct 31Nov 2Nov 4Nov 6Nov 9Nov 13Nov 17Nov 23
24°FNov 4Nov 7Nov 11Nov 14Nov 18Nov 22Nov 26Dec 1Dec 6
20°FNov 13Nov 18Nov 22Nov 26Nov 29Dec 2Dec 6Dec 11Dec 18
16°FNov 22Nov 28Dec 1Dec 5Dec 9Dec 14Dec 19Dec 23Dec 29

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°F195190186181177174169165159
32°F217211206202198194190185177
28°F241235229224221216212207201
24°F266259254249243239235229222
20°F290281276270266261255248242
16°F310302297291286281275268259

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
5,221
Cooling degree days, base 65°F
1,127
Growing degree days, base 40°F
6,094
Growing degree days, base 45°F
4,828
Growing degree days, base 50°F
3,703
Growing degree days, base 55°F
2,709
Growing degree days, base 60°F
1,848

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,12204
February91008
March697354
April35714176
May12687430
June12239676
July1340804
August2292755
September55133529
October31520214
November648044
December97608

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 9 km from Brownsburg. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00053842 (Indianapolis Eagle Creek AP). Public domain.