Spencer climate

Spencer Frost Dates and Growing Season

NOAA 1991-2020 normals for Spencer 1 N, 2.7 km from Spencer, elevation 1326 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Spencer 1 N. 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 1 and the first fall freeze around October 3, a growing season of about 154 days.

Median at 36°F
last May 10, first September 24
Median at 32°F
last May 1, first October 3
Median at 28°F
last April 22, first October 14

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 18May 15May 12May 10May 8May 5May 2Apr 29
32°FMay 14May 9May 6May 4May 1Apr 30Apr 26Apr 23Apr 18
28°FMay 5May 1Apr 28Apr 24Apr 22Apr 18Apr 15Apr 12Apr 8
24°FApr 27Apr 22Apr 18Apr 15Apr 12Apr 9Apr 7Apr 3Mar 31
20°FApr 19Apr 14Apr 10Apr 7Apr 4Apr 1Mar 30Mar 24Mar 17
16°FApr 14Apr 6Apr 3Mar 31Mar 27Mar 23Mar 19Mar 14Mar 10

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 11Sep 16Sep 19Sep 21Sep 24Sep 27Sep 29Oct 2Oct 7
32°FSep 20Sep 24Sep 28Sep 30Oct 3Oct 5Oct 9Oct 13Oct 17
28°FSep 28Oct 2Oct 6Oct 10Oct 14Oct 17Oct 19Oct 22Oct 27
24°FOct 10Oct 16Oct 20Oct 22Oct 24Oct 27Oct 30Nov 1Nov 5
20°FOct 20Oct 24Oct 27Oct 30Nov 1Nov 3Nov 6Nov 9Nov 13
16°FOct 27Nov 1Nov 3Nov 6Nov 8Nov 11Nov 14Nov 18Nov 24

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°F155149145141137133129125119
32°F173166162158154151147141135
28°F193186182177174169165160152
24°F214206201197193189184180173
20°F232224219214209205202197190
16°F248242237233228224220215206

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
7,560
Cooling degree days, base 65°F
713
Growing degree days, base 40°F
4,752
Growing degree days, base 45°F
3,713
Growing degree days, base 50°F
2,782
Growing degree days, base 55°F
1,968
Growing degree days, base 60°F
1,275

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,51700
February1,24300
March982013
April565474
May24043293
June35164579
July9249705
August21176620
September14870381
October5106106
November938011
December1,35300

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 2.7 km from Spencer. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00137844 (Spencer 1 N). Public domain.