Day Heights climate

Day Heights Frost Dates and Growing Season

NOAA 1991-2020 normals for Milford, 5.3 km from Day Heights, elevation 520 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Milford. 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 23 and the first fall freeze around October 18, a growing season of about 177 days.

Median at 36°F
last May 2, first October 9
Median at 32°F
last April 23, first October 18
Median at 28°F
last April 11, first October 27

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 16May 11May 8May 5May 2Apr 30Apr 27Apr 23Apr 19
32°FMay 8May 3Apr 30Apr 25Apr 23Apr 20Apr 17Apr 14Apr 9
28°FApr 28Apr 21Apr 17Apr 14Apr 11Apr 8Apr 5Apr 3Mar 31
24°FApr 14Apr 8Apr 5Apr 3Apr 1Mar 30Mar 26Mar 22Mar 17
20°FApr 3Mar 31Mar 27Mar 24Mar 21Mar 18Mar 14Mar 10Mar 4
16°FMar 26Mar 21Mar 18Mar 15Mar 11Mar 8Mar 3Feb 27Feb 19

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 29Oct 3Oct 5Oct 7Oct 9Oct 11Oct 13Oct 15Oct 18
32°FOct 6Oct 10Oct 13Oct 16Oct 18Oct 20Oct 22Oct 24Oct 28
28°FOct 16Oct 20Oct 23Oct 25Oct 27Oct 30Nov 1Nov 4Nov 9
24°FOct 24Oct 30Nov 1Nov 3Nov 7Nov 10Nov 13Nov 18Nov 26
20°FNov 3Nov 9Nov 13Nov 17Nov 21Nov 26Dec 1Dec 4Dec 11
16°FNov 14Nov 21Nov 27Dec 1Dec 4Dec 8Dec 14Dec 20Dec 27

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°F176170166163159155152147140
32°F193187183180177174170165158
28°F217209205201197193189185177
24°F243234229225221217212207200
20°F272262255250245240235229222
16°F296287281275271265259254244

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
5,134
Cooling degree days, base 65°F
1,083
Growing degree days, base 40°F
6,033
Growing degree days, base 45°F
4,768
Growing degree days, base 50°F
3,636
Growing degree days, base 55°F
2,646
Growing degree days, base 60°F
1,790

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07207
February88505
March705143
April36314175
May12580425
June15232667
July0323787
August2298761
September63122509
October32713194
November630154
December94708

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 5.3 km from Day Heights. 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 USC00335268 (Milford). Public domain.