Davenport Frost Dates and Growing Season

NOAA 1991-2020 normals for Winter Haven, 20.7 km from Davenport, elevation 145 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Winter Haven. 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 38 percent of years at Winter Haven, so there is no typical freeze season.

Median at 36°F: last January 28, first January 5
Median at 32°F: last January 16, first January 9

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 18	Feb 8	Feb 1	Jan 28	Jan 19	Jan 13	Jan 9	Dec 31
32°F	Feb 15	Feb 3	Jan 30	Jan 23	Jan 16	Jan 10	Jan 6	Jan 3	Dec 29
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 10	Dec 19	Dec 27	Jan 1	Jan 5	Jan 10	Jan 16	Jan 25	Feb 5
32°F	Dec 23	Dec 31	Jan 2	Jan 6	Jan 9	Jan 15	Jan 23	Jan 30	Feb 7
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	363	353	345	336	330	322	310	298
32°F	365	365	365	365	365	363	351	338	325
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: 84% of years
32°F or colder: 38% 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: 368
Cooling degree days, base 65°F: 3,755
Growing degree days, base 40°F: 12,512
Growing degree days, base 45°F: 10,689
Growing degree days, base 50°F: 8,874
Growing degree days, base 55°F: 7,082
Growing degree days, base 60°F: 5,355

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	133	55	394
February	70	78	430
March	39	144	571
April	3	263	710
May	0	426	891
June	0	513	963
July	0	578	1,043
August	0	578	1,043
September	0	504	954
October	1	369	832
November	29	164	585
December	93	83	457

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 20.7 km from Davenport. 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 USC00089707 (Winter Haven). Public domain.