Highland climate

Highland Frost Dates and Growing Season

NOAA 1991-2020 normals for Belleville Siu Rsch, 28.8 km from Highland, elevation 450 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Belleville Siu Rsch. 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 12 and the first fall freeze around October 20, a growing season of about 189 days.

Median at 36°F
last April 23, first October 9
Median at 32°F
last April 12, first October 20
Median at 28°F
last March 31, first October 30

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 8May 3Apr 30Apr 26Apr 23Apr 20Apr 17Apr 14Apr 10
32°FApr 28Apr 22Apr 19Apr 15Apr 12Apr 8Apr 5Apr 2Mar 28
28°FApr 16Apr 10Apr 6Apr 3Mar 31Mar 29Mar 25Mar 20Mar 14
24°FApr 6Apr 1Mar 29Mar 25Mar 21Mar 17Mar 14Mar 8Mar 2
20°FMar 27Mar 21Mar 17Mar 13Mar 9Mar 5Mar 2Feb 26Feb 19
16°FMar 18Mar 12Mar 7Mar 3Feb 28Feb 24Feb 18Feb 11Feb 3

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

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°F188181176172168164160155147
32°F209203198194189185180175167
28°F234227221216211207203197188
24°F263253247242237232227220213
20°F286276269263258254248243234
16°F310299293286281275269262253

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
4,209
Cooling degree days, base 65°F
1,579
Growing degree days, base 40°F
7,158
Growing degree days, base 45°F
5,768
Growing degree days, base 50°F
4,520
Growing degree days, base 55°F
3,403
Growing degree days, base 60°F
2,418

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January973010
February748124
March5428105
April23736280
May64148549
June4331777
July0434899
August1379843
September36189604
October21549321
November530593
December859016

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 28.8 km from Highland. 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 USW00013802 (Belleville Siu Rsch). Public domain.