Atlantic climate

Atlantic Frost Dates and Growing Season

NOAA 1991-2020 normals for Atlantic 1 Ne, 1.7 km from Atlantic, elevation 1152 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Atlantic 1 Ne. 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 30 and the first fall freeze around October 2, a growing season of about 153 days.

Median at 36°F
last May 9, first September 25
Median at 32°F
last April 30, first October 2
Median at 28°F
last April 22, first October 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.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 23May 19May 15May 12May 9May 7May 4Apr 30Apr 27
32°FMay 15May 9May 6May 3Apr 30Apr 28Apr 25Apr 22Apr 17
28°FMay 5Apr 30Apr 27Apr 24Apr 22Apr 18Apr 16Apr 13Apr 8
24°FApr 28Apr 22Apr 18Apr 15Apr 13Apr 10Apr 7Apr 3Mar 31
20°FApr 19Apr 13Apr 9Apr 6Apr 4Apr 2Mar 30Mar 26Mar 19
16°FApr 9Apr 4Apr 1Mar 29Mar 26Mar 22Mar 18Mar 13Mar 7

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 11Sep 15Sep 19Sep 21Sep 25Sep 28Oct 1Oct 3Oct 7
32°FSep 17Sep 23Sep 26Sep 29Oct 2Oct 4Oct 7Oct 11Oct 16
28°FSep 27Oct 1Oct 5Oct 8Oct 12Oct 15Oct 18Oct 22Oct 27
24°FOct 8Oct 14Oct 17Oct 20Oct 23Oct 25Oct 28Oct 31Nov 4
20°FOct 17Oct 23Oct 26Oct 30Nov 1Nov 3Nov 5Nov 9Nov 14
16°FOct 25Oct 31Nov 3Nov 5Nov 8Nov 12Nov 15Nov 19Nov 26

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°F155149145141138134129125119
32°F174167161156153150146141134
28°F192185180175171168163158151
24°F213205200196192187183178172
20°F233223218214209206202197190
16°F251243237232227222218212205

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
6,638
Cooling degree days, base 65°F
940
Growing degree days, base 40°F
5,333
Growing degree days, base 45°F
4,215
Growing degree days, base 50°F
3,215
Growing degree days, base 55°F
2,334
Growing degree days, base 60°F
1,574

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,37800
February1,12301
March857127
April4787109
May18062360
June19208639
July3307769
August11243697
September11499441
October43013153
November831019
December1,21501

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 1.7 km from Atlantic. 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 USC00130364 (Atlantic 1 Ne). Public domain.