Watson climate

Watson Frost Dates and Growing Season

NOAA 1991-2020 normals for Baton Rouge Ryan AP, 19.1 km from Watson, elevation 64 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Baton Rouge Ryan AP. 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 25 and the first fall freeze around November 26, a growing season of about 276 days.

Median at 36°F
last March 13, first November 13
Median at 32°F
last February 25, first November 26
Median at 28°F
last February 6, first December 11

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 1Mar 26Mar 21Mar 16Mar 13Mar 8Mar 4Feb 26Feb 20
32°FMar 19Mar 12Mar 7Mar 1Feb 25Feb 20Feb 15Feb 5Jan 29
28°FMar 8Feb 26Feb 19Feb 12Feb 6Feb 1Jan 27Jan 18Jan 4
24°FFeb 23Feb 10Feb 3Jan 30Jan 24Jan 16Jan 11Jan 4Dec 25
20°FFeb 7Feb 1Jan 27Jan 19Jan 14Jan 9Jan 4Dec 30Dec 21
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°FOct 30Nov 3Nov 6Nov 9Nov 13Nov 16Nov 20Nov 25Dec 1
32°FNov 7Nov 13Nov 17Nov 21Nov 26Dec 1Dec 3Dec 8Dec 19
28°FNov 19Nov 27Dec 1Dec 6Dec 11Dec 21Dec 30Jan 5Jan 18
24°FDec 4Dec 12Dec 22Dec 29Jan 2Jan 7Jan 12Jan 20Feb 3
20°FDec 13Dec 25Dec 31Jan 4Jan 8Jan 12Jan 16Jan 23Feb 2
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°F275265258252247241236229221
32°F311299289283276270263257245
28°F351338328318311304295285274
24°F365365365356348340334325310
20°F365365365365365365365355340
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
100% of years
28°F or colder
97% of years
24°F or colder
70% of years
20°F or colder
32% of years
16°F or colder
6% 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
1,534
Cooling degree days, base 65°F
2,818
Growing degree days, base 40°F
10,436
Growing degree days, base 45°F
8,674
Growing degree days, base 50°F
6,997
Growing degree days, base 55°F
5,448
Growing degree days, base 60°F
4,050

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January41813155
February27925207
March15865383
April51141541
May4328789
June0480930
July05531,018
August05501,015
September1415864
October45185606
November21042302
December36921188

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 19.1 km from Watson. 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 USW00013970 (Baton Rouge Ryan AP). Public domain.