Ave Maria Frost Dates and Growing Season

NOAA 1991-2020 normals for Immokalee, 13.9 km from Ave Maria, elevation 35 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Immokalee. 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 43 percent of years at Immokalee, so there is no typical freeze season.

Median at 36°F: last February 2, first January 8
Median at 32°F: last January 23, first January 11
Median at 28°F: last January 12, 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 3	Feb 21	Feb 13	Feb 7	Feb 2	Jan 27	Jan 19	Jan 12	Jan 2
32°F	Feb 18	Feb 8	Feb 2	Jan 28	Jan 23	Jan 17	Jan 10	Jan 4	Dec 31
28°F	Feb 1	Jan 27	Jan 25	Jan 19	Jan 12	Jan 9	Jan 6	Jan 2	Dec 29
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 11	Dec 25	Dec 31	Jan 3	Jan 8	Jan 13	Jan 20	Jan 29	Feb 7
32°F	Dec 26	Jan 1	Jan 4	Jan 8	Jan 11	Jan 19	Jan 26	Feb 1	Feb 10
28°F	Dec 27	Jan 2	Jan 4	Jan 8	Jan 11	Jan 16	Jan 22	Jan 26	Jan 31
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	364	353	343	335	329	320	311	300
32°F	365	365	365	365	365	360	351	338	328
28°F	365	365	365	365	365	365	365	365	360
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: 80% of years
32°F or colder: 43% of years
28°F or colder: 11% 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: 315
Cooling degree days, base 65°F: 3,865
Growing degree days, base 40°F: 12,675
Growing degree days, base 45°F: 10,853
Growing degree days, base 50°F: 9,036
Growing degree days, base 55°F: 7,238
Growing degree days, base 60°F: 5,500

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	114	78	437
February	67	105	459
March	31	161	595
April	5	260	705
May	0	406	871
June	0	504	954
July	0	561	1,026
August	0	566	1,031
September	0	514	965
October	2	396	859
November	23	196	623
December	74	119	512

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 13.9 km from Ave Maria. 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 USC00084210 (Immokalee). Public domain.