Terrytown climate

Terrytown Frost Dates and Growing Season

NOAA 1991-2020 normals for Terrytown 3S, 0.1 km from Terrytown, elevation 10 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Terrytown 3S. 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 February 1 and the first fall freeze around December 31, a growing season of about 330 days.

Median at 36°F
last February 22, first December 9
Median at 32°F
last February 1, first December 31
Median at 28°F
last January 23, first January 8

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°FMar 16Mar 10Mar 4Feb 28Feb 22Feb 15Feb 7Feb 1Jan 23
32°FMar 6Feb 27Feb 16Feb 7Feb 1Jan 27Jan 20Jan 13Jan 2
28°FFeb 26Feb 10Feb 2Jan 29Jan 23Jan 17Jan 11Jan 6Dec 29
24°FFeb 6Feb 1Jan 29Jan 22Jan 17Jan 13Jan 10Jan 7Jan 3
20°F–––––––––
16°F–––––––––

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°FNov 17Nov 24Dec 1Dec 5Dec 9Dec 15Dec 22Dec 30Jan 7
32°FDec 1Dec 10Dec 19Dec 25Dec 31Jan 4Jan 8Jan 15Jan 29
28°FDec 20Dec 27Jan 1Jan 4Jan 8Jan 11Jan 18Jan 27Feb 9
24°FJan 1Jan 2Jan 5Jan 8Jan 11Jan 13Jan 19Jan 25Feb 4
20°F–––––––––
16°F–––––––––

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°F329316308300292286279270258
32°F365355343336330322312303291
28°F365365365365361353344334323
24°F365365365365365365365365346
20°F365365365365365365365365365
16°F365365365365365365365365365

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
90% of years
28°F or colder
56% of years
24°F or colder
19% of years
20°F or colder
4% of years
16°F or colder
0% 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
1,206
Cooling degree days, base 65°F
3,150
Growing degree days, base 40°F
11,082
Growing degree days, base 45°F
9,293
Growing degree days, base 50°F
7,565
Growing degree days, base 55°F
5,942
Growing degree days, base 60°F
4,464

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January35715191
February23625234
March12072423
April32167585
May2366829
June0517967
July05911,056
August05911,055
September0476925
October23245687
November14158375
December29629238

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 0.1 km from Terrytown. 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 USC00168941 (Terrytown 3S). Public domain.