Harvey climate

Harvey Frost Dates and Growing Season

NOAA 1991-2020 normals for Harvey 4NE, 6.1 km from Harvey, elevation 1611 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Harvey 4NE. 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 12 and the first fall freeze around September 26, a growing season of about 135 days.

Median at 36°F
last May 22, first September 18
Median at 32°F
last May 12, first September 26
Median at 28°F
last May 4, first October 4

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 30May 27May 25May 22May 19May 16May 13May 9
32°FMay 25May 21May 17May 14May 12May 9May 7May 4Apr 30
28°FMay 18May 13May 10May 6May 4May 1Apr 28Apr 24Apr 18
24°FMay 9May 4Apr 30Apr 28Apr 25Apr 21Apr 18Apr 15Apr 10
20°FApr 30Apr 25Apr 20Apr 17Apr 14Apr 11Apr 8Apr 6Apr 2
16°FApr 22Apr 16Apr 13Apr 9Apr 7Apr 5Apr 2Mar 31Mar 24

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 5Sep 9Sep 12Sep 15Sep 18Sep 20Sep 22Sep 24Sep 28
32°FSep 14Sep 18Sep 21Sep 24Sep 26Sep 28Oct 1Oct 3Oct 6
28°FSep 23Sep 27Sep 29Oct 2Oct 4Oct 6Oct 9Oct 11Oct 15
24°FOct 1Oct 4Oct 7Oct 10Oct 12Oct 15Oct 18Oct 20Oct 24
20°FOct 8Oct 12Oct 16Oct 18Oct 21Oct 24Oct 26Oct 29Nov 2
16°FOct 17Oct 21Oct 24Oct 27Oct 29Nov 1Nov 4Nov 7Nov 11

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°F133128124120117114111106100
32°F152146142138135132129125119
28°F170164160155151148144139134
24°F189183178174170166162157151
20°F207200196192188184180175168
16°F225217212207203199196190183

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
9,518
Cooling degree days, base 65°F
362
Growing degree days, base 40°F
3,749
Growing degree days, base 45°F
2,838
Growing degree days, base 50°F
2,035
Growing degree days, base 55°F
1,343
Growing degree days, base 60°F
774

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,78100
February1,49100
March1,24501
April738027
May35013192
June9765421
July29143580
August61112516
September25227253
October700144
November1,16902
December1,60700

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 6.1 km from Harvey. 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 USC00324013 (Harvey 4NE). Public domain.