Stephenville climate

Stephenville Frost Dates and Growing Season

NOAA 1991-2020 normals for Stephenville, 3 km from Stephenville, elevation 1290 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Stephenville. 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 29 and the first fall freeze around November 8, a growing season of about 226 days.

Median at 36°F
last April 9, first October 30
Median at 32°F
last March 29, first November 8
Median at 28°F
last March 15, first November 17

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 25Apr 20Apr 17Apr 13Apr 9Apr 5Apr 2Mar 31Mar 23
32°FApr 18Apr 9Apr 4Apr 1Mar 29Mar 25Mar 21Mar 16Mar 9
28°FApr 2Mar 28Mar 23Mar 18Mar 15Mar 11Mar 7Mar 3Feb 25
24°FMar 22Mar 14Mar 10Mar 6Mar 2Feb 27Feb 22Feb 16Feb 5
20°FMar 10Mar 4Feb 26Feb 19Feb 12Feb 6Jan 31Jan 24Jan 11
16°FMar 1Feb 15Feb 8Feb 1Jan 26Jan 21Jan 14Jan 3Dec 19

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 16Oct 21Oct 24Oct 27Oct 30Nov 2Nov 4Nov 8Nov 12
32°FOct 23Oct 29Nov 1Nov 5Nov 8Nov 10Nov 14Nov 19Nov 25
28°FNov 1Nov 6Nov 10Nov 14Nov 17Nov 21Nov 26Nov 30Dec 5
24°FNov 8Nov 15Nov 20Nov 25Nov 30Dec 3Dec 7Dec 13Dec 22
20°FNov 19Nov 27Dec 3Dec 7Dec 13Dec 20Dec 27Jan 3Jan 15
16°FNov 30Dec 9Dec 16Dec 24Dec 31Jan 6Jan 12Jan 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°F227218213209205201196190182
32°F249241236231226220215209202
28°F273265260253248243238232223
24°F304294286279272267261254245
20°F343331321313306299292281269
16°F365365359349342334326315302

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
74% 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
2,484
Cooling degree days, base 65°F
2,502
Growing degree days, base 40°F
9,296
Growing degree days, base 45°F
7,654
Growing degree days, base 50°F
6,145
Growing degree days, base 55°F
4,779
Growing degree days, base 60°F
3,560

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January621258
February4535100
March29326251
April10890440
May20260705
June0461910
July05871,052
August05771,041
September8348790
October93124503
November32220214
December566278

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 km from Stephenville. 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 USW00003969 (Stephenville). Public domain.