Randolph climate

Randolph Frost Dates and Growing Season

NOAA 1991-2020 normals for Rochester, 13.4 km from Randolph, elevation 830 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rochester. 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 May 13 and the first fall freeze around October 2, a growing season of about 141 days.

Median at 36°F
last May 29, first September 23
Median at 32°F
last May 13, first October 2
Median at 28°F
last April 30, first October 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°FJun 10Jun 6Jun 2May 31May 29May 26May 23May 19May 14
32°FMay 29May 24May 21May 17May 13May 10May 7May 3Apr 30
28°FMay 15May 10May 6May 2Apr 30Apr 28Apr 25Apr 22Apr 17
24°FApr 30Apr 26Apr 22Apr 20Apr 17Apr 14Apr 11Apr 8Apr 5
20°FApr 19Apr 14Apr 10Apr 8Apr 6Apr 4Apr 2Apr 1Mar 28
16°FApr 9Apr 6Apr 4Apr 2Apr 1Mar 31Mar 27Mar 23Mar 18

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 10Sep 14Sep 17Sep 20Sep 23Sep 26Sep 28Oct 1Oct 4
32°FSep 19Sep 25Sep 29Oct 1Oct 2Oct 4Oct 7Oct 11Oct 17
28°FOct 1Oct 4Oct 7Oct 10Oct 13Oct 16Oct 20Oct 25Nov 1
24°FOct 8Oct 14Oct 19Oct 23Oct 27Oct 31Nov 2Nov 6Nov 13
20°FOct 24Oct 29Nov 1Nov 5Nov 9Nov 12Nov 16Nov 19Nov 25
16°FNov 5Nov 10Nov 14Nov 17Nov 20Nov 23Nov 25Nov 29Dec 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°F13512912412111711310910497
32°F160154149145141136132127120
28°F186178172168164160157151144
24°F211204199194191185181176168
20°F233226222218215211206202195
16°F252245240236233229225220214

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
7,883
Cooling degree days, base 65°F
271
Growing degree days, base 40°F
3,806
Growing degree days, base 45°F
2,819
Growing degree days, base 50°F
1,963
Growing degree days, base 55°F
1,241
Growing degree days, base 60°F
668

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,42700
February1,24700
March1,11803
April694130
May3539167
June12346375
July34102533
August5284498
September20327286
October554163
November85208
December1,22600

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 13.4 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 USC00436893 (Rochester). Public domain.