Thomas climate

Thomas Frost Dates and Growing Season

NOAA 1991-2020 normals for Davis 3SE, 8 km from Thomas, elevation 3715 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Davis 3SE. 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 9 and the first fall freeze around October 10, a growing season of about 153 days.

Median at 36°F
last May 21, first October 1
Median at 32°F
last May 9, first October 10
Median at 28°F
last April 30, first October 20

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

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 20Sep 24Sep 26Sep 29Oct 1Oct 2Oct 5Oct 8Oct 12
32°FSep 27Oct 2Oct 5Oct 7Oct 10Oct 13Oct 15Oct 18Oct 22
28°FOct 7Oct 11Oct 14Oct 17Oct 20Oct 22Oct 25Oct 29Nov 1
24°FOct 16Oct 21Oct 25Oct 28Oct 31Nov 1Nov 3Nov 6Nov 12
20°FOct 27Oct 31Nov 2Nov 4Nov 7Nov 10Nov 14Nov 18Nov 24
16°FNov 4Nov 7Nov 12Nov 15Nov 18Nov 22Nov 26Nov 30Dec 6

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°F153145141135132128124119113
32°F173166162157153148144139132
28°F192187182177173169165160152
24°F216208203199195190186181173
20°F237230225220215211207202195
16°F261252245240236231227221214

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
7,194
Cooling degree days, base 65°F
188
Growing degree days, base 40°F
3,997
Growing degree days, base 45°F
2,919
Growing degree days, base 50°F
1,982
Growing degree days, base 55°F
1,203
Growing degree days, base 60°F
590

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27401
February1,08603
March978013
April600171
May3287201
June12237367
July4574494
August6950447
September20417278
October533189
November834016
December1,12203

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 8 km from Thomas. 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 USC00462211 (Davis 3SE). Public domain.