Highlands climate

Highlands Frost Dates and Growing Season

NOAA 1991-2020 normals for Highlands, 0.4 km from Highlands, elevation 3850 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Highlands. 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 30 and the first fall freeze around October 15, a growing season of about 167 days.

Median at 36°F
last May 10, first October 5
Median at 32°F
last April 30, first October 15
Median at 28°F
last April 16, first October 26

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 27May 21May 17May 13May 10May 8May 5May 1Apr 27
32°FMay 17May 10May 6May 3Apr 30Apr 26Apr 22Apr 18Apr 13
28°FMay 5Apr 28Apr 23Apr 20Apr 16Apr 12Apr 8Apr 4Mar 30
24°FApr 20Apr 12Apr 7Apr 4Apr 1Mar 30Mar 26Mar 20Mar 15
20°FApr 7Apr 2Mar 29Mar 25Mar 21Mar 18Mar 14Mar 9Mar 2
16°FMar 29Mar 23Mar 18Mar 14Mar 9Mar 4Feb 28Feb 20Feb 8

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 23Sep 27Sep 30Oct 2Oct 5Oct 8Oct 11Oct 15Oct 19
32°FOct 3Oct 7Oct 10Oct 13Oct 15Oct 18Oct 21Oct 25Oct 29
28°FOct 13Oct 17Oct 20Oct 23Oct 26Oct 28Oct 31Nov 2Nov 6
24°FOct 22Oct 26Oct 30Nov 1Nov 4Nov 7Nov 10Nov 15Nov 21
20°FNov 1Nov 4Nov 8Nov 11Nov 16Nov 20Nov 26Dec 1Dec 8
16°FNov 10Nov 18Nov 24Nov 30Dec 3Dec 8Dec 14Dec 22Jan 1

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°F164159153150146142138133127
32°F188182176172167163159153147
28°F213206200196192188182177170
24°F241233226221217212208202194
20°F270260254247242237232225215
16°F307294286279272265258250241

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
5,369
Cooling degree days, base 65°F
242
Growing degree days, base 40°F
4,747
Growing degree days, base 45°F
3,467
Growing degree days, base 50°F
2,374
Growing degree days, base 55°F
1,468
Growing degree days, base 60°F
745

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January98902
February80204
March691029
April4401100
May2248264
June6247435
July1498549
August2972508
September12816340
October4151119
November680020
December89605

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 0.4 km from Highlands. 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 USC00314055 (Highlands). Public domain.