Green Spring climate

Green Spring Frost Dates and Growing Season

NOAA 1991-2020 normals for Louisville Bowman Fld, 10.7 km from Green Spring, elevation 540 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Louisville Bowman Fld. 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 3 and the first fall freeze around November 3, a growing season of about 214 days.

Median at 36°F
last April 16, first October 23
Median at 32°F
last April 3, first November 3
Median at 28°F
last March 22, first November 13

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 3Apr 26Apr 22Apr 19Apr 16Apr 13Apr 10Apr 6Apr 2
32°FApr 19Apr 14Apr 9Apr 5Apr 3Mar 31Mar 28Mar 24Mar 18
28°FApr 5Apr 1Mar 29Mar 26Mar 22Mar 19Mar 15Mar 10Mar 4
24°FMar 26Mar 21Mar 18Mar 14Mar 9Mar 6Mar 2Feb 26Feb 20
20°FMar 17Mar 10Mar 6Mar 2Feb 28Feb 24Feb 18Feb 12Feb 5
16°FMar 8Mar 2Feb 26Feb 20Feb 14Feb 9Feb 4Jan 31Jan 21

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 12Oct 16Oct 19Oct 21Oct 23Oct 26Oct 28Oct 31Nov 3
32°FOct 21Oct 25Oct 29Nov 1Nov 3Nov 5Nov 8Nov 11Nov 16
28°FNov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 19Nov 24Dec 1
24°FNov 8Nov 13Nov 16Nov 20Nov 24Nov 29Dec 3Dec 7Dec 15
20°FNov 18Nov 25Nov 30Dec 4Dec 8Dec 13Dec 19Dec 24Dec 31
16°FDec 1Dec 7Dec 13Dec 19Dec 23Dec 27Jan 1Jan 7Jan 15

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°F209203198193189185180176169
32°F232226221217214210205200193
28°F262253246242237233229223215
24°F288279272267261256250245237
20°F312303296290285280273267258
16°F334326320313306302296288279

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
99% 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
4,151
Cooling degree days, base 65°F
1,543
Growing degree days, base 40°F
7,115
Growing degree days, base 45°F
5,713
Growing degree days, base 50°F
4,455
Growing degree days, base 55°F
3,343
Growing degree days, base 60°F
2,373

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January930016
February738025
March552795
April24436277
May70140536
June3313760
July0422887
August0391855
September32194612
October23238292
November536276
December812024

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 10.7 km from Green Spring. 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 USW00013810 (Louisville Bowman Fld). Public domain.