Highmore climate

Highmore Frost Dates and Growing Season

NOAA 1991-2020 normals for Highmore 1 W, 1.1 km from Highmore, elevation 1888 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Highmore 1 W. 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 May 12 and the first fall freeze around October 1, a growing season of about 142 days.

Median at 36°F
last May 21, first September 22
Median at 32°F
last May 12, first October 1
Median at 28°F
last May 2, first October 10

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°FJun 5May 31May 27May 24May 21May 18May 14May 11May 7
32°FMay 28May 22May 17May 14May 12May 8May 6May 2Apr 28
28°FMay 17May 12May 8May 4May 2Apr 30Apr 27Apr 21Apr 14
24°FMay 10May 4Apr 30Apr 28Apr 24Apr 20Apr 15Apr 12Apr 7
20°FMay 1Apr 26Apr 20Apr 16Apr 13Apr 9Apr 6Apr 3Mar 29
16°FApr 21Apr 14Apr 10Apr 7Apr 4Apr 1Mar 29Mar 22Mar 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°FSep 10Sep 14Sep 17Sep 20Sep 22Sep 25Sep 28Oct 1Oct 5
32°FSep 17Sep 22Sep 25Sep 29Oct 1Oct 4Oct 7Oct 10Oct 14
28°FSep 25Sep 30Oct 3Oct 6Oct 10Oct 12Oct 16Oct 20Oct 25
24°FOct 3Oct 8Oct 12Oct 16Oct 19Oct 23Oct 25Oct 29Nov 3
20°FOct 11Oct 18Oct 22Oct 25Oct 29Nov 1Nov 4Nov 7Nov 11
16°FOct 21Oct 27Oct 31Nov 2Nov 5Nov 8Nov 10Nov 14Nov 19

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°F143136132128124120116111103
32°F160154150145142137133128120
28°F179172167163158154148143136
24°F199191185180176172167162154
20°F217210205201196192187181173
16°F237230224219214210205199191

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
7,661
Cooling degree days, base 65°F
718
Growing degree days, base 40°F
4,701
Growing degree days, base 45°F
3,663
Growing degree days, base 50°F
2,740
Growing degree days, base 55°F
1,938
Growing degree days, base 60°F
1,261

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,50000
February1,22801
March991012
April589267
May28024248
June60116506
July11263717
August21224668
September14083403
October5226109
November957010
December1,36200

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 1.1 km from Highmore. 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 USC00393832 (Highmore 1 W). Public domain.