Harbour Heights Frost Dates and Growing Season

NOAA 1991-2020 normals for Punta Gorda 4 Ese, 8.5 km from Harbour Heights, elevation 20 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Punta Gorda 4 Ese. 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 42 percent of years at Punta Gorda 4 Ese, so there is no typical freeze season.

Median at 36°F: last February 1, first January 10
Median at 32°F: last January 21, first January 14

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 1	Feb 20	Feb 11	Feb 5	Feb 1	Jan 28	Jan 22	Jan 15	Jan 6
32°F	Feb 14	Feb 6	Feb 1	Jan 28	Jan 21	Jan 16	Jan 11	Jan 6	Jan 1
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 21	Dec 29	Jan 1	Jan 6	Jan 10	Jan 15	Jan 22	Jan 29	Feb 9
32°F	Dec 27	Jan 2	Jan 6	Jan 9	Jan 14	Jan 19	Jan 26	Feb 1	Feb 9
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	364	354	345	337	330	323	315	302
32°F	365	365	365	365	365	365	356	344	330
28°F	365	365	365	365	365	365	365	365	365
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: 42% of years
28°F or colder: 10% 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: 260
Cooling degree days, base 65°F: 4,204
Growing degree days, base 40°F: 13,069
Growing degree days, base 45°F: 11,245
Growing degree days, base 50°F: 9,426
Growing degree days, base 55°F: 7,621
Growing degree days, base 60°F: 5,865

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	100	89	458
February	52	115	484
March	24	190	631
April	2	298	746
May	0	446	911
June	0	546	996
July	0	600	1,065
August	0	609	1,074
September	0	550	1,001
October	1	420	884
November	17	210	644
December	64	130	534

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 8.5 km from Harbour Heights. 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 USC00087397 (Punta Gorda 4 Ese). Public domain.