Lutz Frost Dates and Growing Season

NOAA 1991-2020 normals for Tampa Intl AP, 22.4 km from Lutz, elevation 19 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tampa Intl AP. 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 35 percent of years at Tampa Intl AP, so there is no typical freeze season.

Median at 36°F: last January 29, first January 8
Median at 32°F: last January 20, first January 12

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 14	Feb 5	Feb 1	Jan 29	Jan 22	Jan 15	Jan 9	Dec 31
32°F	Feb 10	Feb 2	Jan 31	Jan 25	Jan 20	Jan 13	Jan 9	Jan 4	Dec 27
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 14	Dec 25	Dec 30	Jan 3	Jan 8	Jan 14	Jan 22	Jan 29	Feb 8
32°F	Dec 23	Dec 30	Jan 3	Jan 7	Jan 12	Jan 16	Jan 23	Jan 29	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	362	353	344	336	329	322	311
32°F	365	365	365	365	365	365	358	347	335
28°F	365	365	365	365	365	365	365	365	363
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: 74% of years
32°F or colder: 35% of years
28°F or colder: 9% 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: 434
Cooling degree days, base 65°F: 3,928
Growing degree days, base 40°F: 12,620
Growing degree days, base 45°F: 10,799
Growing degree days, base 50°F: 8,987
Growing degree days, base 55°F: 7,206
Growing degree days, base 60°F: 5,505

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	152	61	384
February	88	81	416
March	44	154	576
April	7	274	717
May	0	448	913
June	0	538	989
July	0	583	1,048
August	0	589	1,054
September	0	532	983
October	3	388	849
November	34	178	594
December	105	102	466

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 22.4 km from Lutz. 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 USW00012842 (Tampa Intl AP). Public domain.