Randolph climate

Randolph Frost Dates and Growing Season

NOAA 1991-2020 normals for Boonton 1 Se, 16.3 km from Randolph, elevation 280 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Boonton 1 Se. 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 17 and the first fall freeze around October 23, a growing season of about 189 days.

Median at 36°F
last May 1, first October 12
Median at 32°F
last April 17, first October 23
Median at 28°F
last April 4, first November 2

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 18May 11May 8May 5May 1Apr 28Apr 24Apr 21Apr 17
32°FMay 5Apr 30Apr 24Apr 20Apr 17Apr 14Apr 11Apr 8Apr 4
28°FApr 18Apr 13Apr 9Apr 6Apr 4Apr 2Mar 31Mar 28Mar 21
24°FApr 6Apr 2Mar 31Mar 27Mar 25Mar 21Mar 18Mar 15Mar 9
20°FMar 29Mar 24Mar 20Mar 18Mar 15Mar 12Mar 8Mar 4Feb 28
16°FMar 21Mar 16Mar 13Mar 9Mar 6Mar 2Feb 28Feb 23Feb 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°FOct 1Oct 4Oct 6Oct 9Oct 12Oct 14Oct 18Oct 22Oct 29
32°FOct 8Oct 13Oct 17Oct 20Oct 23Oct 26Oct 30Nov 1Nov 6
28°FOct 19Oct 24Oct 28Nov 1Nov 2Nov 5Nov 9Nov 12Nov 17
24°FOct 31Nov 4Nov 8Nov 11Nov 14Nov 16Nov 20Nov 24Dec 1
20°FNov 10Nov 15Nov 19Nov 23Nov 27Dec 1Dec 4Dec 9Dec 18
16°FNov 20Nov 28Dec 2Dec 6Dec 11Dec 17Dec 22Dec 28Jan 5

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°F186178174169166161157151145
32°F209202198193189184180175166
28°F231225220216212208204199192
24°F256248243239234231227221214
20°F281273267262258253248242235
16°F306298291286280275270264254

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
5,631
Cooling degree days, base 65°F
865
Growing degree days, base 40°F
5,401
Growing degree days, base 45°F
4,196
Growing degree days, base 50°F
3,151
Growing degree days, base 55°F
2,245
Growing degree days, base 60°F
1,485

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11301
February95501
March82009
April4514101
May19141321
June26169593
July1302766
August4247708
September8397465
October3717155
November665030
December95203

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 16.3 km from Randolph. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00280907 (Boonton 1 Se). Public domain.