Manchester climate

Manchester Frost Dates and Growing Season

NOAA 1991-2020 normals for Sunderland 2, 9.2 km from Manchester, elevation 900 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sunderland 2. 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 13 and the first fall freeze around September 29, a growing season of about 137 days.

Median at 36°F
last May 28, first September 19
Median at 32°F
last May 13, first September 29
Median at 28°F
last May 1, first October 9

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

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

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°F13312712111711311010610295
32°F157150146142137134130125117
28°F184177171166161157153147141
24°F211204198193188184179173164
20°F236229223219216211207200193
16°F261254247243239234230224217

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
7,351
Cooling degree days, base 65°F
321
Growing degree days, base 40°F
4,036
Growing degree days, base 45°F
3,002
Growing degree days, base 50°F
2,108
Growing degree days, base 55°F
1,353
Growing degree days, base 60°F
750

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,34500
February1,15900
March1,04005
April633243
May31815200
June9865418
July27122559
August4892508
September19525290
October533272
November810010
December1,14402

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 9.2 km from Manchester. 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 USC00438160 (Sunderland 2). Public domain.