Trinity climate

Trinity Frost Dates and Growing Season

NOAA 1991-2020 normals for Decatur Pryor Fld, 14 km from Trinity, elevation 592 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Decatur Pryor Fld. 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 March 27 and the first fall freeze around November 3, a growing season of about 221 days.

Median at 36°F
last April 5, first October 25
Median at 32°F
last March 27, first November 3
Median at 28°F
last March 14, first November 15

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°FApr 20Apr 15Apr 11Apr 8Apr 5Apr 2Mar 31Mar 28Mar 22
32°FApr 10Apr 5Apr 2Mar 30Mar 27Mar 24Mar 19Mar 15Mar 8
28°FApr 1Mar 27Mar 22Mar 17Mar 14Mar 9Mar 5Feb 28Feb 23
24°FMar 21Mar 14Mar 8Mar 4Feb 28Feb 24Feb 19Feb 13Feb 3
20°FMar 9Mar 2Feb 25Feb 19Feb 12Feb 6Jan 31Jan 26Jan 13
16°FFeb 27Feb 16Feb 7Feb 2Jan 30Jan 25Jan 18Jan 10Jan 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°FOct 13Oct 18Oct 21Oct 23Oct 25Oct 28Oct 31Nov 2Nov 6
32°FOct 22Oct 26Oct 29Nov 1Nov 3Nov 6Nov 9Nov 13Nov 20
28°FNov 1Nov 4Nov 7Nov 11Nov 15Nov 18Nov 22Nov 28Dec 4
24°FNov 8Nov 15Nov 19Nov 24Nov 29Dec 2Dec 6Dec 12Dec 26
20°FNov 21Nov 29Dec 3Dec 8Dec 13Dec 22Dec 30Jan 4Jan 14
16°FDec 7Dec 17Dec 26Jan 1Jan 4Jan 9Jan 14Jan 21Feb 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°F222214209205201198193187181
32°F246238231226221216212208201
28°F274263256250245240234227219
24°F308297288281275268262254245
20°F343333325315307299293284269
16°F365364354345338332325317303

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
97% of years
16°F or colder
81% 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
3,119
Cooling degree days, base 65°F
1,828
Growing degree days, base 40°F
8,081
Growing degree days, base 45°F
6,526
Growing degree days, base 50°F
5,114
Growing degree days, base 55°F
3,859
Growing degree days, base 60°F
2,764

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January733041
February553256
March3909164
April15855356
May32185619
June0363813
July0457922
August0429894
September13258694
October15663383
November4336117
December649155

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 14 km from Trinity. 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 USW00053852 (Decatur Pryor Fld). Public domain.