Greenfield climate

Greenfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Greenfield, 0.7 km from Greenfield, elevation 869 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Greenfield. 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 19 and the first fall freeze around October 22, a growing season of about 185 days.

Median at 36°F
last May 1, first October 12
Median at 32°F
last April 19, first October 22
Median at 28°F
last April 7, 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 16May 11May 7May 3May 1Apr 27Apr 24Apr 21Apr 16
32°FMay 7May 1Apr 26Apr 22Apr 19Apr 17Apr 13Apr 11Apr 6
28°FApr 23Apr 17Apr 13Apr 10Apr 7Apr 4Apr 2Mar 30Mar 24
24°FApr 10Apr 5Apr 2Mar 31Mar 29Mar 25Mar 22Mar 18Mar 12
20°FApr 1Mar 28Mar 24Mar 20Mar 18Mar 14Mar 11Mar 7Mar 1
16°FMar 23Mar 18Mar 15Mar 11Mar 8Mar 5Mar 1Feb 25Feb 16

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 30Oct 4Oct 7Oct 10Oct 12Oct 15Oct 17Oct 20Oct 24
32°FOct 9Oct 14Oct 17Oct 20Oct 22Oct 24Oct 26Oct 29Nov 1
28°FOct 21Oct 25Oct 28Oct 30Nov 1Nov 3Nov 6Nov 10Nov 16
24°FNov 1Nov 3Nov 6Nov 10Nov 13Nov 16Nov 20Nov 25Dec 1
20°FNov 8Nov 13Nov 17Nov 20Nov 24Nov 28Dec 1Dec 6Dec 14
16°FNov 16Nov 23Nov 27Dec 1Dec 4Dec 9Dec 13Dec 18Dec 23

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°F182176171167164160157151144
32°F203196192188185181177171164
28°F226218214210206202198193186
24°F255245239234229224220215208
20°F278270263258253248244237228
16°F300292286281274270264259250

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
5,706
Cooling degree days, base 65°F
953
Growing degree days, base 40°F
5,668
Growing degree days, base 45°F
4,460
Growing degree days, base 50°F
3,388
Growing degree days, base 55°F
2,442
Growing degree days, base 60°F
1,629

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,18903
February97304
March784138
April4139146
May15875391
June21207636
July3288750
August5244704
September77113488
October35615187
November695036
December1,03205

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 0.7 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 USC00123527 (Greenfield). Public domain.