Llano climate

Llano Frost Dates and Growing Season

NOAA 1991-2020 normals for Llano, 2.7 km from Llano, elevation 1020 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Llano. 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 20 and the first fall freeze around November 10, a growing season of about 235 days.

Median at 36°F
last April 4, first November 3
Median at 32°F
last March 20, first November 10
Median at 28°F
last March 5, first November 21

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 22Apr 16Apr 12Apr 8Apr 4Apr 1Mar 28Mar 22Mar 15
32°FApr 11Apr 4Mar 31Mar 25Mar 20Mar 16Mar 12Mar 6Feb 28
28°FMar 26Mar 19Mar 14Mar 10Mar 5Mar 1Feb 25Feb 19Feb 9
24°FMar 13Mar 6Mar 2Feb 24Feb 19Feb 11Feb 3Jan 28Jan 18
20°FMar 2Feb 20Feb 7Jan 31Jan 26Jan 19Jan 12Jan 1Dec 19
16°FFeb 8Jan 30Jan 23Jan 18Jan 13Jan 6Dec 31Dec 24Dec 13

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 30Nov 1Nov 3Nov 5Nov 9Nov 12Nov 18
32°FOct 28Nov 1Nov 4Nov 7Nov 10Nov 14Nov 17Nov 23Nov 30
28°FNov 4Nov 8Nov 12Nov 17Nov 21Nov 25Nov 30Dec 3Dec 10
24°FNov 14Nov 20Nov 25Nov 29Dec 2Dec 6Dec 12Dec 21Jan 1
20°FNov 25Dec 1Dec 6Dec 12Dec 19Dec 26Jan 1Jan 7Jan 20
16°FDec 3Dec 12Dec 19Dec 26Jan 1Jan 4Jan 11Jan 16Jan 27

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°F240231224218213208203198190
32°F264253246240235230224217207
28°F292281274267261255250242233
24°F332318310301293286278269257
20°F365357347339332323314303289
16°F365365365365365360350343330

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
99% of years
20°F or colder
88% of years
16°F or colder
50% 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
2,014
Cooling degree days, base 65°F
2,799
Growing degree days, base 40°F
9,982
Growing degree days, base 45°F
8,275
Growing degree days, base 50°F
6,680
Growing degree days, base 55°F
5,229
Growing degree days, base 60°F
3,930

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January533382
February36510142
March22041313
April75126504
May9313769
June0498948
July06061,071
August06081,072
September4395842
October64164569
November25931261
December4865107

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 2.7 km from Llano. 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 USC00415272 (Llano). Public domain.