Cortez Frost Dates and Growing Season

NOAA 1991-2020 normals for Bradenton 5 Ese, 18.4 km from Cortez, elevation 20 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bradenton 5 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 31 percent of years at Bradenton 5 Ese, so there is no typical freeze season.

Median at 36°F: last January 27, first January 8
Median at 32°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	Feb 23	Feb 12	Feb 4	Jan 31	Jan 27	Jan 19	Jan 14	Jan 7	Dec 31
32°F	Feb 9	Feb 2	Jan 29	Jan 24	Jan 16	Jan 10	Jan 8	Jan 2	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 11	Dec 21	Dec 30	Jan 3	Jan 8	Jan 13	Jan 20	Jan 27	Feb 5
32°F	Dec 20	Dec 30	Jan 4	Jan 8	Jan 11	Jan 16	Jan 24	Jan 30	Feb 5
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	349	341	334	329	321	310
32°F	365	365	365	365	365	365	358	345	334
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: 72% of years
32°F or colder: 31% of years
28°F or colder: 7% 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: 437
Cooling degree days, base 65°F: 3,773
Growing degree days, base 40°F: 12,461
Growing degree days, base 45°F: 10,641
Growing degree days, base 50°F: 8,831
Growing degree days, base 55°F: 7,053
Growing degree days, base 60°F: 5,354

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	149	59	386
February	87	84	420
March	43	148	571
April	8	248	690
May	0	414	879
June	0	522	972
July	0	577	1,042
August	0	578	1,043
September	0	513	963
October	4	368	829
November	37	168	581
December	110	94	456

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 18.4 km from Cortez. 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 USC00080945 (Bradenton 5 Ese). Public domain.