Diamond climate

Diamond Frost Dates and Growing Season

NOAA 1991-2020 normals for Diamond 2W, 3.6 km from Diamond, elevation 1070 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Diamond 2W. 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 22, a growing season of about 184 days.

Median at 36°F
last April 30, first October 11
Median at 32°F
last April 18, first October 22
Median at 28°F
last April 6, 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 13May 7May 4May 2Apr 30Apr 26Apr 23Apr 19Apr 13
32°FMay 3Apr 29Apr 25Apr 21Apr 18Apr 15Apr 12Apr 7Apr 2
28°FApr 22Apr 18Apr 13Apr 10Apr 6Apr 3Mar 31Mar 27Mar 20
24°FApr 12Apr 6Apr 2Mar 30Mar 26Mar 22Mar 18Mar 12Mar 5
20°FApr 3Mar 26Mar 20Mar 15Mar 11Mar 7Mar 3Feb 28Feb 20
16°FMar 19Mar 13Mar 8Mar 4Mar 1Feb 26Feb 21Feb 15Feb 4

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 29Oct 2Oct 5Oct 9Oct 11Oct 14Oct 17Oct 20Oct 24
32°FOct 7Oct 13Oct 16Oct 19Oct 22Oct 24Oct 26Oct 30Nov 2
28°FOct 17Oct 21Oct 25Oct 27Oct 30Nov 1Nov 4Nov 8Nov 14
24°FOct 25Oct 31Nov 2Nov 5Nov 9Nov 12Nov 17Nov 21Nov 27
20°FNov 2Nov 7Nov 11Nov 16Nov 21Nov 26Nov 30Dec 4Dec 11
16°FNov 11Nov 19Nov 25Nov 30Dec 3Dec 7Dec 12Dec 18Dec 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°F182176171167164160156153145
32°F207199193188184180175170163
28°F229222217211207202198192185
24°F253245238234228224219213205
20°F280271265258253247242235226
16°F307296290282276270263257247

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
4,346
Cooling degree days, base 65°F
1,440
Growing degree days, base 40°F
6,876
Growing degree days, base 45°F
5,492
Growing degree days, base 50°F
4,262
Growing degree days, base 55°F
3,176
Growing degree days, base 60°F
2,233

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January953010
February745125
March561695
April29228236
May9996465
June7277720
July1416880
August2388851
September43188597
October24837285
November546383
December849015

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 3.6 km from Diamond. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00232240 (Diamond 2W). Public domain.