Randolph climate

Randolph Frost Dates and Growing Season

NOAA 1991-2020 normals for Blue Hill Coop, 8.1 km from Randolph, elevation 625 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Blue Hill Coop. 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 18 and the first fall freeze around October 26, a growing season of about 190 days.

Median at 36°F
last April 30, first October 14
Median at 32°F
last April 18, first October 26
Median at 28°F
last April 6, first November 5

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 12May 6May 3May 1Apr 30Apr 27Apr 24Apr 22Apr 18
32°FApr 30Apr 25Apr 22Apr 20Apr 18Apr 16Apr 13Apr 10Apr 7
28°FApr 18Apr 14Apr 10Apr 7Apr 6Apr 4Apr 2Mar 31Mar 28
24°FApr 7Apr 4Apr 2Mar 31Mar 30Mar 28Mar 24Mar 21Mar 16
20°FApr 1Mar 29Mar 26Mar 23Mar 21Mar 18Mar 16Mar 13Mar 9
16°FMar 26Mar 21Mar 18Mar 15Mar 13Mar 10Mar 8Mar 4Mar 1

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 2Oct 5Oct 9Oct 11Oct 14Oct 17Oct 20Oct 24Oct 29
32°FOct 9Oct 15Oct 19Oct 22Oct 26Oct 29Nov 1Nov 3Nov 8
28°FOct 23Oct 30Nov 1Nov 3Nov 5Nov 8Nov 11Nov 14Nov 19
24°FNov 4Nov 8Nov 11Nov 14Nov 17Nov 19Nov 22Nov 28Dec 2
20°FNov 14Nov 18Nov 22Nov 25Nov 29Dec 1Dec 4Dec 8Dec 15
16°FNov 23Nov 28Dec 1Dec 5Dec 8Dec 12Dec 16Dec 21Dec 27

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°F185178174171167164160155148
32°F207202197193190187182178170
28°F230223219215212209205201195
24°F252246241236232228225221216
20°F272265261257253249245240234
16°F292286278274270266261257250

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
6,210
Cooling degree days, base 65°F
677
Growing degree days, base 40°F
4,936
Growing degree days, base 45°F
3,793
Growing degree days, base 50°F
2,799
Growing degree days, base 55°F
1,945
Growing degree days, base 60°F
1,233

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,19301
February1,02901
March915010
April540368
May25825252
June66111496
July7248705
August11209663
September10074426
October3947145
November692029
December1,00603

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 8.1 km from Randolph. 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 USC00190736 (Blue Hill Coop). Public domain.