Old Tappan climate

Old Tappan Frost Dates and Growing Season

NOAA 1991-2020 normals for Dobbs Ferry-Ardsley, 13.1 km from Old Tappan, elevation 200 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Dobbs Ferry-Ardsley. 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 26, a growing season of about 189 days.

Median at 36°F
last May 2, first October 12
Median at 32°F
last April 20, first October 26
Median at 28°F
last April 4, first November 7

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

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 1Oct 4Oct 6Oct 10Oct 12Oct 15Oct 19Oct 24Oct 31
32°FOct 10Oct 15Oct 19Oct 23Oct 26Oct 30Nov 2Nov 5Nov 10
28°FOct 23Oct 30Nov 2Nov 5Nov 7Nov 10Nov 14Nov 18Nov 23
24°FNov 7Nov 11Nov 15Nov 18Nov 22Nov 24Nov 28Dec 2Dec 8
20°FNov 18Nov 24Nov 28Dec 1Dec 3Dec 7Dec 12Dec 17Dec 23
16°FDec 1Dec 5Dec 10Dec 15Dec 20Dec 24Dec 29Jan 2Jan 10

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°F185178173168164160156152146
32°F210204198194189185181175168
28°F238230225220217213208203197
24°F266260254248243238234230223
20°F294285280273268264258253246
16°F319309304299294289284277267

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
5,119
Cooling degree days, base 65°F
917
Growing degree days, base 40°F
5,718
Growing degree days, base 45°F
4,446
Growing degree days, base 50°F
3,333
Growing degree days, base 55°F
2,375
Growing degree days, base 60°F
1,570

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,04002
February87601
March749020
April4147119
May16246352
June25169594
July1311775
August3268730
September61106495
October31311194
November594044
December88207

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 13.1 km from Old Tappan. 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 USC00302129 (Dobbs Ferry-Ardsley). Public domain.