Sullivan climate

Sullivan Frost Dates and Growing Season

NOAA 1991-2020 normals for Acadia Np, 17 km from Sullivan, elevation 470 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Acadia Np. 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 27 and the first fall freeze around October 22, a growing season of about 177 days.

Median at 36°F
last May 8, first October 8
Median at 32°F
last April 27, first October 22
Median at 28°F
last April 15, first November 2

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 14May 11May 8May 6May 3Apr 30Apr 27
32°FMay 8May 4May 1Apr 29Apr 27Apr 24Apr 22Apr 19Apr 15
28°FApr 27Apr 22Apr 19Apr 17Apr 15Apr 12Apr 9Apr 7Apr 4
24°FApr 15Apr 10Apr 7Apr 5Apr 4Apr 2Apr 1Mar 30Mar 24
20°FApr 6Apr 4Apr 2Mar 31Mar 29Mar 25Mar 22Mar 19Mar 14
16°FApr 1Mar 29Mar 25Mar 22Mar 19Mar 17Mar 14Mar 12Mar 8

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 26Oct 1Oct 3Oct 5Oct 8Oct 11Oct 15Oct 20Oct 25
32°FOct 6Oct 11Oct 15Oct 19Oct 22Oct 25Oct 29Nov 1Nov 5
28°FOct 18Oct 24Oct 28Nov 1Nov 2Nov 5Nov 7Nov 11Nov 16
24°FOct 30Nov 3Nov 7Nov 11Nov 14Nov 16Nov 19Nov 22Nov 27
20°FNov 9Nov 14Nov 18Nov 21Nov 23Nov 26Nov 28Dec 1Dec 5
16°FNov 18Nov 23Nov 26Nov 29Dec 1Dec 3Dec 6Dec 10Dec 15

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°F171164159155151148144139134
32°F196190185182177174169163157
28°F218213209205201198194189183
24°F240235230226222219215211204
20°F257252248244241237233229223
16°F274268264260257253249243236

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
6,835
Cooling degree days, base 65°F
411
Growing degree days, base 40°F
4,296
Growing degree days, base 45°F
3,216
Growing degree days, base 50°F
2,291
Growing degree days, base 55°F
1,512
Growing degree days, base 60°F
885

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27700
February1,08600
March98304
April630026
May33110173
June9460416
July14161612
August15139589
September13339358
October447299
November743013
December1,08200

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 17 km from Sullivan. 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 USC00170100 (Acadia Np). Public domain.