Port LaBelle Frost Dates and Growing Season

NOAA 1991-2020 normals for Ortona Lock 2, 10.6 km from Port LaBelle, elevation 20 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ortona Lock 2. 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 27 and the first fall freeze around January 11, a growing season of about 348 days.

Median at 36°F: last February 10, first January 1
Median at 32°F: last January 27, first January 11
Median at 28°F: last January 16, 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 12	Mar 1	Feb 24	Feb 18	Feb 10	Feb 4	Jan 31	Jan 21	Jan 12
32°F	Feb 27	Feb 18	Feb 8	Feb 1	Jan 27	Jan 20	Jan 14	Jan 9	Jan 1
28°F	Feb 10	Feb 3	Jan 29	Jan 22	Jan 16	Jan 12	Jan 8	Jan 4	Dec 30
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 4	Dec 13	Dec 21	Dec 28	Jan 1	Jan 6	Jan 12	Jan 18	Jan 29
32°F	Dec 18	Dec 27	Jan 1	Jan 6	Jan 11	Jan 16	Jan 24	Jan 31	Feb 10
28°F	Dec 26	Jan 1	Jan 4	Jan 8	Jan 11	Jan 16	Jan 25	Feb 1	Feb 9
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	353	340	333	325	319	312	304	297	285
32°F	365	365	365	358	348	340	332	323	309
28°F	365	365	365	365	365	365	365	359	342
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: 95% of years
32°F or colder: 69% of years
28°F or colder: 26% of years
24°F or colder: 4% 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: 439
Cooling degree days, base 65°F: 3,386
Growing degree days, base 40°F: 12,073
Growing degree days, base 45°F: 10,252
Growing degree days, base 50°F: 8,441
Growing degree days, base 55°F: 6,665
Growing degree days, base 60°F: 4,963

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	153	51	374
February	89	80	414
March	51	129	543
April	7	228	671
May	0	355	820
June	0	452	902
July	0	510	975
August	0	529	994
September	0	464	914
October	4	342	803
November	33	157	575
December	102	91	459

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 10.6 km from Port LaBelle. 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 USC00086657 (Ortona Lock 2). Public domain.