Lockhart Frost Dates and Growing Season

NOAA 1991-2020 normals for Orlando Executive AP, 13.5 km from Lockhart, elevation 108 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Orlando Executive AP. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

A freeze (32°F or colder) happens in only 35 percent of years at Orlando Executive AP, so there is no typical freeze season.

Median at 36°F: last January 25, first January 6
Median at 32°F: last January 17, first January 13

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	Feb 22	Feb 10	Feb 4	Jan 31	Jan 25	Jan 17	Jan 12	Jan 7	Dec 31
32°F	Feb 9	Feb 3	Jan 30	Jan 23	Jan 17	Jan 13	Jan 8	Jan 3	Dec 26
28°F	–	–	–	–	–	–	–	–	–
24°F	–	–	–	–	–	–	–	–	–
20°F	–	–	–	–	–	–	–	–	–
16°F	–	–	–	–	–	–	–	–	–

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	Dec 12	Dec 22	Dec 28	Jan 1	Jan 6	Jan 12	Jan 16	Jan 24	Feb 4
32°F	Dec 23	Dec 29	Jan 3	Jan 8	Jan 13	Jan 18	Jan 22	Jan 29	Feb 6
28°F	–	–	–	–	–	–	–	–	–
24°F	–	–	–	–	–	–	–	–	–
20°F	–	–	–	–	–	–	–	–	–
16°F	–	–	–	–	–	–	–	–	–

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	365	365	358	351	342	335	329	320	308
32°F	365	365	365	365	365	365	358	346	334
28°F	365	365	365	365	365	365	365	365	364
24°F	365	365	365	365	365	365	365	365	365
20°F	365	365	365	365	365	365	365	365	365
16°F	365	365	365	365	365	365	365	365	365

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder: 75% of years
32°F or colder: 35% of years
28°F or colder: 9% of years
24°F or colder: 0% of years
20°F or colder: 0% of years
16°F or colder: 0% 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: 468
Cooling degree days, base 65°F: 3,694
Growing degree days, base 40°F: 12,351
Growing degree days, base 45°F: 10,531
Growing degree days, base 50°F: 8,723
Growing degree days, base 55°F: 6,951
Growing degree days, base 60°F: 5,259

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	164	56	369
February	95	75	403
March	42	145	569
April	8	248	690
May	0	417	882
June	0	511	962
July	0	572	1,037
August	0	575	1,040
September	0	501	951
October	4	356	817
November	36	154	569
December	120	83	434

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 13.5 km from Lockhart. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00012841 (Orlando Executive AP). Public domain.