Greenfield climate

Greenfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Greenfield, 1.8 km from Greenfield, elevation 1316 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 25 and the first fall freeze around October 12, a growing season of about 170 days.

Median at 36°F
last May 4, first October 2
Median at 32°F
last April 25, first October 12
Median at 28°F
last April 16, first October 23

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 12May 9May 6May 4May 2Apr 30Apr 27Apr 23
32°FMay 7May 3May 1Apr 28Apr 25Apr 22Apr 19Apr 16Apr 12
28°FApr 29Apr 25Apr 22Apr 19Apr 16Apr 13Apr 10Apr 7Apr 3
24°FApr 22Apr 17Apr 13Apr 10Apr 7Apr 4Apr 1Mar 28Mar 22
20°FApr 14Apr 9Apr 5Apr 1Mar 29Mar 26Mar 21Mar 17Mar 10
16°FApr 5Mar 31Mar 27Mar 22Mar 19Mar 15Mar 11Mar 8Mar 3

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 19Sep 24Sep 27Sep 30Oct 2Oct 5Oct 8Oct 12Oct 17
32°FSep 26Oct 1Oct 5Oct 9Oct 12Oct 15Oct 18Oct 22Oct 26
28°FOct 6Oct 13Oct 16Oct 19Oct 23Oct 25Oct 28Nov 1Nov 5
24°FOct 18Oct 23Oct 27Oct 30Nov 1Nov 3Nov 6Nov 10Nov 14
20°FOct 25Oct 31Nov 3Nov 5Nov 8Nov 11Nov 14Nov 17Nov 23
16°FNov 2Nov 6Nov 10Nov 12Nov 15Nov 18Nov 23Nov 28Dec 3

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°F168162158155150147143139133
32°F189183179174170166162157149
28°F208202198194190186181176169
24°F227221215211208204200194186
20°F248239233228224219215211203
16°F265257251247242237232226219

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
6,628
Cooling degree days, base 65°F
868
Growing degree days, base 40°F
5,296
Growing degree days, base 45°F
4,174
Growing degree days, base 50°F
3,164
Growing degree days, base 55°F
2,269
Growing degree days, base 60°F
1,500

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,38900
February1,12401
March852128
April4805109
May18951342
June23180607
July3290752
August10235690
September10594444
October40612167
November822023
December1,22601

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 1.8 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 USC00133438 (Greenfield). Public domain.