Monticello climate

Monticello Frost Dates and Growing Season

NOAA 1991-2020 normals for Canton L&d 20, 16.9 km from Monticello, elevation 490 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Canton L&d 20. 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 11 and the first fall freeze around October 23, a growing season of about 194 days.

Median at 36°F
last April 23, first October 14
Median at 32°F
last April 11, first October 23
Median at 28°F
last April 2, first November 1

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 7May 3Apr 30Apr 27Apr 23Apr 20Apr 17Apr 14Apr 10
32°FApr 29Apr 22Apr 18Apr 15Apr 11Apr 9Apr 6Apr 2Mar 29
28°FApr 15Apr 9Apr 6Apr 4Apr 2Mar 31Mar 28Mar 23Mar 17
24°FApr 7Apr 2Mar 31Mar 27Mar 24Mar 21Mar 17Mar 12Mar 6
20°FMar 31Mar 26Mar 21Mar 17Mar 14Mar 10Mar 7Mar 4Feb 27
16°FMar 22Mar 16Mar 12Mar 9Mar 6Mar 3Mar 1Feb 24Feb 17

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 30Oct 5Oct 8Oct 11Oct 14Oct 17Oct 19Oct 22Oct 26
32°FOct 10Oct 14Oct 18Oct 21Oct 23Oct 25Oct 27Oct 30Nov 4
28°FOct 21Oct 25Oct 28Oct 30Nov 1Nov 4Nov 7Nov 11Nov 16
24°FNov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 18Nov 23Nov 29
20°FNov 7Nov 11Nov 14Nov 18Nov 22Nov 25Nov 29Dec 3Dec 8
16°FNov 13Nov 20Nov 25Nov 28Dec 1Dec 5Dec 8Dec 14Dec 20

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°F192185181176173169165160153
32°F211205200197194190185180173
28°F234227222217213209205201194
24°F257249244239235231226221213
20°F277269263258254249245239232
16°F294286280274270266261255247

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
5,742
Cooling degree days, base 65°F
1,041
Growing degree days, base 40°F
5,784
Growing degree days, base 45°F
4,579
Growing degree days, base 50°F
3,503
Growing degree days, base 55°F
2,551
Growing degree days, base 60°F
1,726

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,23201
February99405
March762140
April39910149
May14769393
June16221655
July1328792
August4275736
September76118494
October34417198
November702138
December1,06503

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 16.9 km from Monticello. 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 USC00231275 (Canton L&d 20). Public domain.