Rockport climate

Rockport Frost Dates and Growing Season

NOAA 1991-2020 normals for Malvern, 1.3 km from Rockport, elevation 300 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Malvern. 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 March 31 and the first fall freeze around November 5, a growing season of about 220 days.

Median at 36°F
last April 12, first October 28
Median at 32°F
last March 31, first November 5
Median at 28°F
last March 18, first November 16

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°FApr 26Apr 22Apr 18Apr 15Apr 12Apr 8Apr 5Mar 31Mar 26
32°FApr 16Apr 11Apr 6Apr 3Mar 31Mar 28Mar 24Mar 18Mar 11
28°FApr 6Mar 31Mar 27Mar 23Mar 18Mar 14Mar 8Mar 3Feb 26
24°FMar 22Mar 15Mar 11Mar 6Mar 2Feb 28Feb 24Feb 19Feb 10
20°FMar 9Mar 2Feb 26Feb 21Feb 15Feb 10Feb 4Jan 30Jan 20
16°FFeb 28Feb 18Feb 11Feb 4Jan 31Jan 27Jan 21Jan 12Jan 1

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 16Oct 20Oct 23Oct 26Oct 28Oct 31Nov 1Nov 4Nov 9
32°FOct 25Oct 30Nov 1Nov 3Nov 5Nov 8Nov 11Nov 15Nov 22
28°FNov 2Nov 6Nov 9Nov 12Nov 16Nov 19Nov 23Nov 29Dec 3
24°FNov 9Nov 14Nov 20Nov 24Nov 28Dec 2Dec 5Dec 11Dec 20
20°FNov 21Nov 28Dec 4Dec 10Dec 16Dec 22Dec 26Jan 1Jan 9
16°FDec 5Dec 13Dec 21Dec 26Dec 31Jan 3Jan 9Jan 16Feb 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°F219212207203199195190186179
32°F244235229225220215210206196
28°F269260254248242237230225216
24°F301290282275270264257250239
20°F336327315308302295286278266
16°F365358348340334327318309298

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
99% of years
16°F or colder
86% 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
3,225
Cooling degree days, base 65°F
1,916
Growing degree days, base 40°F
8,075
Growing degree days, base 45°F
6,537
Growing degree days, base 50°F
5,154
Growing degree days, base 55°F
3,924
Growing degree days, base 60°F
2,844

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January757126
February585245
March39710158
April16845338
May34176608
June1370819
July0494959
August0465930
September11278717
October14870397
November4395117
December686139

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 1.3 km from Rockport. 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 USC00034562 (Malvern). Public domain.