Greenfield climate

Greenfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Washington Court House, 20.7 km from Greenfield, elevation 957 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Washington Court House. 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 23 and the first fall freeze around October 21, a growing season of about 181 days.

Median at 36°F
last May 2, first October 10
Median at 32°F
last April 23, first October 21
Median at 28°F
last April 11, first November 1

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 19May 13May 9May 5May 2Apr 30Apr 27Apr 23Apr 19
32°FMay 8May 2Apr 29Apr 26Apr 23Apr 21Apr 18Apr 15Apr 10
28°FApr 25Apr 20Apr 17Apr 14Apr 11Apr 8Apr 5Apr 2Mar 29
24°FApr 14Apr 9Apr 5Apr 3Apr 1Mar 29Mar 26Mar 22Mar 17
20°FApr 4Mar 31Mar 27Mar 24Mar 21Mar 18Mar 15Mar 10Mar 4
16°FMar 28Mar 22Mar 18Mar 15Mar 10Mar 7Mar 3Feb 27Feb 19

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°FSep 27Oct 2Oct 5Oct 7Oct 10Oct 12Oct 14Oct 18Oct 22
32°FOct 8Oct 13Oct 16Oct 18Oct 21Oct 23Oct 25Oct 28Oct 31
28°FOct 20Oct 24Oct 28Oct 30Nov 1Nov 3Nov 5Nov 9Nov 14
24°FOct 31Nov 2Nov 4Nov 7Nov 11Nov 14Nov 17Nov 22Nov 28
20°FNov 6Nov 11Nov 15Nov 18Nov 22Nov 26Nov 30Dec 3Dec 8
16°FNov 14Nov 20Nov 26Nov 30Dec 4Dec 8Dec 12Dec 19Dec 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°F178173169164160156152147140
32°F198193189185181177173169162
28°F222215211206203199196191185
24°F246238233229226222218213206
20°F272263257252247243237232226
16°F296287281274268263258252243

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
5,615
Cooling degree days, base 65°F
830
Growing degree days, base 40°F
5,549
Growing degree days, base 45°F
4,328
Growing degree days, base 50°F
3,244
Growing degree days, base 55°F
2,298
Growing degree days, base 60°F
1,491

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,15303
February95504
March779138
April4065138
May16463373
June22176604
July3257719
August7215673
September8399468
October35413181
November695136
December99506

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 20.7 km from Greenfield. 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 USC00338794 (Washington Court House). Public domain.