Deltona Frost Dates and Growing Season

NOAA 1991-2020 normals for Sanford, 9.7 km from Deltona, elevation 12 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sanford. 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 January 26 and the first fall freeze around January 12, a growing season of about 359 days.

Median at 36°F: last February 4, first January 6
Median at 32°F: last January 26, first January 12
Median at 28°F: last January 13, first January 11

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	Mar 6	Feb 26	Feb 17	Feb 10	Feb 4	Jan 31	Jan 24	Jan 16	Jan 8
32°F	Feb 24	Feb 12	Feb 6	Jan 31	Jan 26	Jan 19	Jan 12	Jan 6	Dec 31
28°F	Feb 6	Jan 31	Jan 27	Jan 19	Jan 13	Jan 10	Jan 6	Dec 31	Dec 25
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 9	Dec 19	Dec 27	Jan 1	Jan 6	Jan 11	Jan 16	Jan 24	Feb 6
32°F	Dec 20	Dec 28	Jan 2	Jan 7	Jan 12	Jan 18	Jan 24	Jan 31	Feb 10
28°F	Dec 19	Dec 29	Jan 3	Jan 7	Jan 11	Jan 14	Jan 23	Jan 29	Feb 5
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	354	342	334	328	322	314	306	298
32°F	365	365	365	365	359	348	338	331	318
28°F	365	365	365	365	365	365	365	365	348
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: 88% of years
32°F or colder: 51% of years
28°F or colder: 15% of years
24°F or colder: 1% 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: 609
Cooling degree days, base 65°F: 3,408
Growing degree days, base 40°F: 11,925
Growing degree days, base 45°F: 10,107
Growing degree days, base 50°F: 8,309
Growing degree days, base 55°F: 6,561
Growing degree days, base 60°F: 4,911

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	203	38	317
February	129	49	347
March	68	112	510
April	13	208	645
May	1	372	835
June	0	489	939
July	0	558	1,023
August	0	560	1,025
September	0	486	936
October	6	331	791
November	47	139	542
December	142	67	400

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 9.7 km from Deltona. 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 USC00087982 (Sanford). Public domain.