Spencer climate

Spencer Frost Dates and Growing Season

NOAA 1991-2020 normals for Spencer, 0.8 km from Spencer, elevation 549 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Spencer. 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 20 and the first fall freeze around October 20, a growing season of about 180 days.

Median at 36°F
last May 1, first October 10
Median at 32°F
last April 20, first October 20
Median at 28°F
last April 7, first October 31

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 18May 12May 7May 3May 1Apr 29Apr 25Apr 22Apr 17
32°FMay 7May 1Apr 27Apr 23Apr 20Apr 17Apr 14Apr 11Apr 6
28°FApr 24Apr 19Apr 14Apr 10Apr 7Apr 4Apr 2Mar 31Mar 24
24°FApr 10Apr 5Apr 1Mar 31Mar 28Mar 24Mar 20Mar 15Mar 8
20°FMar 31Mar 28Mar 23Mar 19Mar 16Mar 12Mar 8Mar 3Feb 25
16°FMar 24Mar 18Mar 14Mar 11Mar 6Mar 2Feb 27Feb 21Feb 12

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 28Oct 2Oct 5Oct 8Oct 10Oct 12Oct 15Oct 19Oct 23
32°FOct 7Oct 11Oct 15Oct 17Oct 20Oct 23Oct 25Oct 28Nov 1
28°FOct 16Oct 21Oct 25Oct 28Oct 31Nov 1Nov 3Nov 6Nov 12
24°FOct 28Nov 1Nov 3Nov 6Nov 9Nov 12Nov 17Nov 21Nov 28
20°FNov 5Nov 10Nov 14Nov 18Nov 22Nov 26Dec 1Dec 3Dec 10
16°FNov 13Nov 20Nov 25Nov 30Dec 2Dec 5Dec 11Dec 17Dec 23

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°F178172168163160156152147140
32°F199193188184180176172166159
28°F225219213208204200196190182
24°F252244238232228224220214207
20°F276267261256251246242235228
16°F301291284279274268262256247

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
5,407
Cooling degree days, base 65°F
987
Growing degree days, base 40°F
5,823
Growing degree days, base 45°F
4,579
Growing degree days, base 50°F
3,477
Growing degree days, base 55°F
2,510
Growing degree days, base 60°F
1,676

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,12505
February92007
March732247
April38611160
May14971395
June22206635
July2303766
August5259719
September75116494
October34318197
November671143
December97809

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 0.8 km from Spencer. 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 USC00128290 (Spencer). Public domain.