Andover climate

Andover Frost Dates and Growing Season

NOAA 1991-2020 normals for Lawrence, 5.2 km from Andover, elevation 50 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lawrence. 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 13 and the first fall freeze around October 28, a growing season of about 198 days.

Median at 36°F
last April 25, first October 16
Median at 32°F
last April 13, first October 28
Median at 28°F
last April 3, first November 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°FMay 10May 4May 2Apr 29Apr 25Apr 23Apr 20Apr 17Apr 12
32°FApr 29Apr 23Apr 19Apr 17Apr 13Apr 10Apr 7Apr 4Apr 1
28°FApr 17Apr 11Apr 7Apr 5Apr 3Apr 1Mar 29Mar 25Mar 18
24°FApr 5Apr 2Mar 30Mar 26Mar 22Mar 19Mar 16Mar 13Mar 8
20°FMar 30Mar 24Mar 20Mar 16Mar 13Mar 11Mar 8Mar 5Feb 28
16°FMar 22Mar 16Mar 12Mar 9Mar 6Mar 3Feb 28Feb 24Feb 18

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 2Oct 6Oct 10Oct 13Oct 16Oct 19Oct 22Oct 26Oct 30
32°FOct 13Oct 18Oct 22Oct 26Oct 28Nov 1Nov 3Nov 6Nov 10
28°FOct 27Nov 1Nov 3Nov 6Nov 9Nov 11Nov 15Nov 18Nov 25
24°FNov 6Nov 12Nov 15Nov 18Nov 22Nov 25Nov 29Dec 2Dec 7
20°FNov 18Nov 23Nov 26Nov 30Dec 2Dec 5Dec 8Dec 12Dec 20
16°FNov 28Dec 1Dec 5Dec 9Dec 12Dec 17Dec 20Dec 25Jan 1

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°F194187182177173170166159152
32°F218211206202198194189184176
28°F241234229224221217213208202
24°F263256251246242238235229222
20°F285277272267263259254249242
16°F305298292287282278273267260

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
5,898
Cooling degree days, base 65°F
793
Growing degree days, base 40°F
5,212
Growing degree days, base 45°F
4,032
Growing degree days, base 50°F
3,006
Growing degree days, base 55°F
2,125
Growing degree days, base 60°F
1,388

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,16701
February99801
March859112
April497580
May22031285
June43141548
July4278739
August6241700
September8491459
October3757149
November666029
December98003

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 5.2 km from Andover. 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 USC00194105 (Lawrence). Public domain.