Brunswick climate

Brunswick Frost Dates and Growing Season

NOAA 1991-2020 normals for Brunswick Nas, 3 km from Brunswick, elevation 70 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Brunswick Nas. 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 2 and the first fall freeze around October 10, a growing season of about 160 days.

Median at 36°F
last May 13, first October 1
Median at 32°F
last May 2, first October 10
Median at 28°F
last April 22, first October 23

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 26May 21May 18May 15May 13May 10May 7May 5May 2
32°FMay 14May 9May 6May 4May 2Apr 30Apr 29Apr 27Apr 24
28°FMay 1Apr 28Apr 26Apr 24Apr 22Apr 20Apr 17Apr 15Apr 10
24°FApr 22Apr 18Apr 16Apr 12Apr 10Apr 7Apr 5Apr 2Mar 31
20°FApr 12Apr 6Apr 4Apr 2Mar 31Mar 28Mar 24Mar 19Mar 15
16°FApr 1Mar 28Mar 24Mar 21Mar 18Mar 15Mar 13Mar 11Mar 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 20Sep 24Sep 27Sep 30Oct 1Oct 3Oct 5Oct 8Oct 12
32°FSep 29Oct 2Oct 5Oct 8Oct 10Oct 13Oct 16Oct 20Oct 27
28°FOct 8Oct 12Oct 16Oct 19Oct 23Oct 27Oct 30Nov 2Nov 7
24°FOct 20Oct 26Oct 29Nov 1Nov 4Nov 7Nov 10Nov 14Nov 20
20°FNov 1Nov 7Nov 11Nov 14Nov 17Nov 20Nov 23Nov 26Dec 1
16°FNov 13Nov 18Nov 21Nov 25Nov 27Nov 30Dec 1Dec 5Dec 10

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°F155150146142138136132129124
32°F177171167163160157153149143
28°F201194190187183179175171165
24°F226219215211207203200196190
20°F251243239235231226221216210
16°F271265260256252248244239232

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
7,341
Cooling degree days, base 65°F
352
Growing degree days, base 40°F
4,021
Growing degree days, base 45°F
3,000
Growing degree days, base 50°F
2,120
Growing degree days, base 55°F
1,383
Growing degree days, base 60°F
786

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,36400
February1,17000
March1,01701
April674016
May3497155
June10750394
July16151600
August23118560
September16526316
October511170
November80609
December1,13901

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 3 km from Brunswick. 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 USW00014611 (Brunswick Nas). Public domain.