Boerne climate

Boerne Frost Dates and Growing Season

NOAA 1991-2020 normals for Boerne, 0.5 km from Boerne, elevation 1445 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Boerne. 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 15 and the first fall freeze around November 13, a growing season of about 243 days.

Median at 36°F
last April 1, first November 4
Median at 32°F
last March 15, first November 13
Median at 28°F
last March 2, first November 27

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

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 4Nov 6Nov 10Nov 14Nov 21
32°FOct 31Nov 3Nov 6Nov 10Nov 13Nov 17Nov 22Nov 28Dec 4
28°FNov 5Nov 12Nov 17Nov 22Nov 27Dec 1Dec 5Dec 10Dec 21
24°FNov 17Nov 24Nov 30Dec 5Dec 11Dec 19Dec 27Jan 3Jan 15
20°FDec 1Dec 9Dec 17Dec 26Jan 1Jan 4Jan 12Jan 22Feb 10
16°FDec 9Dec 24Dec 29Jan 1Jan 5Jan 10Jan 17Jan 22Feb 4

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°F244234228222218213208201193
32°F270261254248243238232226216
28°F306294284276270263258249239
24°F349334325315305298291280268
20°F365365365357348338330319306
16°F365365365365365365365360340

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
96% of years
20°F or colder
70% of years
16°F or colder
30% 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
1,916
Cooling degree days, base 65°F
2,480
Growing degree days, base 40°F
9,746
Growing degree days, base 45°F
8,026
Growing degree days, base 50°F
6,414
Growing degree days, base 55°F
4,938
Growing degree days, base 60°F
3,620

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4984100
February34711154
March20842324
April73112492
May11269724
June0432882
July0519984
August05361,001
September4358804
October64159563
November25233268
December4595118

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 0.5 km from Boerne. 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 USC00410902 (Boerne). Public domain.