Johnson County climate

Johnson County Frost Dates and Growing Season

NOAA 1991-2020 normals for Cleburne, 8.2 km from Johnson County, elevation 783 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cleburne. 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 17 and the first fall freeze around November 12, a growing season of about 240 days.

Median at 36°F
last March 31, first November 3
Median at 32°F
last March 17, first November 12
Median at 28°F
last March 6, first November 25

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

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 21Oct 26Oct 29Nov 1Nov 3Nov 6Nov 9Nov 13Nov 18
32°FOct 30Nov 3Nov 6Nov 9Nov 12Nov 16Nov 19Nov 25Dec 1
28°FNov 6Nov 11Nov 16Nov 21Nov 25Nov 30Dec 3Dec 7Dec 15
24°FNov 14Nov 22Nov 29Dec 3Dec 7Dec 13Dec 18Dec 25Jan 1
20°FNov 30Dec 5Dec 12Dec 18Dec 25Dec 31Jan 3Jan 12Jan 27
16°FDec 10Dec 19Dec 26Jan 1Jan 3Jan 9Jan 15Jan 25Feb 5

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°F240232226221217213207201193
32°F265257251245240235229223215
28°F294284276269263257251245236
24°F327315306299293287279270258
20°F365352343334327320310302289
16°F365365365365363353345334321

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
92% of years
16°F or colder
54% 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
2,442
Cooling degree days, base 65°F
2,484
Growing degree days, base 40°F
9,310
Growing degree days, base 45°F
7,658
Growing degree days, base 50°F
6,138
Growing degree days, base 55°F
4,763
Growing degree days, base 60°F
3,543

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January619156
February451499
March29022244
April10182436
May15242692
June0455904
July05781,043
August05811,046
September5369814
October85128513
November31319213
December563377

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 8.2 km from Johnson County. 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 USC00411800 (Cleburne). Public domain.