Alloway climate

Alloway Frost Dates and Growing Season

NOAA 1991-2020 normals for Seabrook Farms, 14.7 km from Alloway, elevation 104 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Seabrook Farms. 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 April 10 and the first fall freeze around November 1, a growing season of about 205 days.

Median at 36°F
last April 23, first October 21
Median at 32°F
last April 10, first November 1
Median at 28°F
last March 29, first November 13

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°FMay 8May 3Apr 30Apr 27Apr 23Apr 20Apr 17Apr 14Apr 8
32°FApr 25Apr 20Apr 16Apr 12Apr 10Apr 6Apr 3Mar 31Mar 28
28°FApr 11Apr 6Apr 3Mar 31Mar 29Mar 26Mar 22Mar 18Mar 12
24°FMar 30Mar 26Mar 22Mar 19Mar 16Mar 13Mar 9Mar 5Feb 28
20°FMar 21Mar 17Mar 13Mar 9Mar 6Mar 3Feb 28Feb 23Feb 14
16°FMar 13Mar 6Mar 2Feb 27Feb 23Feb 18Feb 12Feb 5Jan 31

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°FOct 7Oct 12Oct 14Oct 17Oct 21Oct 25Oct 28Nov 1Nov 5
32°FOct 16Oct 22Oct 26Oct 30Nov 1Nov 4Nov 7Nov 11Nov 15
28°FOct 28Nov 3Nov 6Nov 10Nov 13Nov 16Nov 19Nov 24Nov 30
24°FNov 11Nov 16Nov 20Nov 24Nov 28Dec 1Dec 5Dec 11Dec 17
20°FNov 23Dec 1Dec 4Dec 9Dec 13Dec 17Dec 21Dec 26Jan 3
16°FDec 7Dec 13Dec 20Dec 25Dec 30Jan 2Jan 7Jan 13Jan 21

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°F202194189185180176171166158
32°F225218213208205201196189183
28°F254244238234230226222217208
24°F281272266261257253248242235
20°F306298292286280275270264257
16°F332324316310305301296290281

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
99% 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
4,784
Cooling degree days, base 65°F
1,135
Growing degree days, base 40°F
6,180
Growing degree days, base 45°F
4,858
Growing degree days, base 50°F
3,698
Growing degree days, base 55°F
2,697
Growing degree days, base 60°F
1,842

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January99005
February83606
March706133
April37812150
May14265390
June18220653
July0364829
August1307770
September42147555
October27720234
November554161
December840013

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 14.7 km from Alloway. 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 USC00287936 (Seabrook Farms). Public domain.