Flagler climate

Flagler Frost Dates and Growing Season

NOAA 1991-2020 normals for Flagler 1S, 1.4 km from Flagler, elevation 4921 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Flagler 1S. 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 May 5 and the first fall freeze around October 8, a growing season of about 155 days.

Median at 36°F
last May 16, first September 29
Median at 32°F
last May 5, first October 8
Median at 28°F
last April 26, first October 16

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.

Threshold10%20%30%40%50%60%70%80%90%
36°FJun 1May 27May 22May 19May 16May 13May 10May 7May 2
32°FMay 20May 14May 10May 8May 5May 2Apr 30Apr 27Apr 22
28°FMay 8May 4May 1Apr 29Apr 26Apr 23Apr 20Apr 16Apr 11
24°FApr 29Apr 24Apr 20Apr 17Apr 14Apr 11Apr 6Apr 2Mar 25
20°FApr 19Apr 14Apr 9Apr 5Apr 1Mar 28Mar 23Mar 18Mar 11
16°FApr 10Apr 3Mar 28Mar 23Mar 19Mar 14Mar 9Mar 4Feb 27

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.

Threshold10%20%30%40%50%60%70%80%90%
36°FSep 18Sep 22Sep 25Sep 27Sep 29Oct 1Oct 4Oct 6Oct 10
32°FSep 27Oct 1Oct 3Oct 6Oct 8Oct 10Oct 12Oct 15Oct 18
28°FOct 5Oct 8Oct 11Oct 13Oct 16Oct 18Oct 20Oct 23Oct 27
24°FOct 13Oct 17Oct 19Oct 22Oct 25Oct 28Oct 31Nov 2Nov 7
20°FOct 21Oct 26Oct 30Nov 1Nov 3Nov 6Nov 10Nov 14Nov 19
16°FOct 26Nov 1Nov 4Nov 8Nov 11Nov 15Nov 19Nov 23Nov 28

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.

Threshold10%20%30%40%50%60%70%80%90%
36°F153147143140136132127122115
32°F172166162158155151147142135
28°F190184179176172169165160154
24°F215208202198194189184179172
20°F240232226221217212207202194
16°F262253248243238233226220213

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% 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
5,817
Cooling degree days, base 65°F
828
Growing degree days, base 40°F
5,300
Growing degree days, base 45°F
4,094
Growing degree days, base 50°F
3,051
Growing degree days, base 55°F
2,164
Growing degree days, base 60°F
1,427

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,05302
February89603
March719032
April479298
May23135295
June36165579
July6294753
August11240694
September11288434
October4414134
November762026
December1,07202

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 1.4 km from Flagler. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00052932 (Flagler 1S). Public domain.