Millburn climate

Millburn Frost Dates and Growing Season

NOAA 1991-2020 normals for Canoe Brook, 4.7 km from Millburn, elevation 180 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Canoe Brook. 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 27, a growing season of about 189 days.

Median at 36°F
last April 30, first October 15
Median at 32°F
last April 18, first October 27
Median at 28°F
last April 3, first November 6

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 17May 10May 6May 4Apr 30Apr 28Apr 25Apr 21Apr 17
32°FMay 6May 1Apr 27Apr 22Apr 18Apr 15Apr 12Apr 8Apr 3
28°FApr 19Apr 14Apr 10Apr 6Apr 3Apr 1Mar 30Mar 25Mar 19
24°FApr 4Mar 31Mar 28Mar 25Mar 21Mar 18Mar 15Mar 11Mar 4
20°FMar 27Mar 22Mar 18Mar 14Mar 11Mar 8Mar 4Feb 28Feb 23
16°FMar 18Mar 11Mar 7Mar 3Feb 28Feb 26Feb 21Feb 16Feb 9

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 6Oct 9Oct 12Oct 15Oct 18Oct 22Oct 26Oct 31
32°FOct 11Oct 16Oct 20Oct 23Oct 27Oct 30Nov 1Nov 5Nov 10
28°FOct 22Oct 28Nov 1Nov 3Nov 6Nov 9Nov 13Nov 16Nov 22
24°FNov 4Nov 8Nov 13Nov 16Nov 19Nov 23Nov 28Dec 1Dec 8
20°FNov 14Nov 21Nov 26Dec 1Dec 4Dec 8Dec 13Dec 18Dec 25
16°FDec 1Dec 6Dec 12Dec 17Dec 21Dec 26Dec 30Jan 4Jan 14

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°F186180175170166162158152144
32°F212204199195189184179173166
28°F238230225220216212208202195
24°F266258252247243238234228222
20°F295286278273267262257251242
16°F316308303298293288281275266

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
5,262
Cooling degree days, base 65°F
1,023
Growing degree days, base 40°F
5,776
Growing degree days, base 45°F
4,530
Growing degree days, base 50°F
3,434
Growing degree days, base 55°F
2,486
Growing degree days, base 60°F
1,681

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,06302
February91302
March769122
April4159125
May16854357
June25196621
July1340804
August3288750
September59122514
October32813191
November615039
December90407

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 4.7 km from Millburn. 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 USC00281335 (Canoe Brook). Public domain.