Cass County climate

Cass County Frost Dates and Growing Season

NOAA 1991-2020 normals for Atlanta, 17.4 km from Cass County, elevation 315 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Atlanta. 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 19 and the first fall freeze around November 11, a growing season of about 237 days.

Median at 36°F
last April 3, first November 1
Median at 32°F
last March 19, first November 11
Median at 28°F
last March 5, first November 25

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 20Apr 14Apr 10Apr 6Apr 3Mar 31Mar 26Mar 22Mar 14
32°FApr 6Apr 1Mar 27Mar 23Mar 19Mar 15Mar 10Mar 4Feb 26
28°FMar 23Mar 17Mar 13Mar 9Mar 5Mar 1Feb 26Feb 19Feb 9
24°FMar 12Mar 6Mar 1Feb 24Feb 16Feb 9Feb 3Jan 29Jan 19
20°FMar 2Feb 18Feb 10Feb 4Jan 31Jan 26Jan 20Jan 11Dec 31
16°FFeb 13Feb 4Jan 31Jan 26Jan 20Jan 15Jan 9Jan 2Dec 25

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 20Oct 24Oct 28Oct 31Nov 1Nov 4Nov 8Nov 12Nov 18
32°FOct 28Nov 1Nov 4Nov 7Nov 11Nov 16Nov 20Nov 26Dec 1
28°FNov 5Nov 11Nov 15Nov 20Nov 25Nov 30Dec 3Dec 8Dec 18
24°FNov 19Nov 25Dec 1Dec 5Dec 11Dec 18Dec 25Jan 1Jan 8
20°FDec 3Dec 15Dec 22Dec 28Jan 1Jan 5Jan 11Jan 16Feb 1
16°FDec 18Dec 28Jan 1Jan 4Jan 9Jan 13Jan 17Jan 28Feb 4

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°F236228222217212207203197191
32°F262254247242237232226220212
28°F296285278271265259253247237
24°F332321313305299293283275264
20°F365358348341334328319308297
16°F365365365365365361353342332

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
99% of years
20°F or colder
87% of years
16°F or colder
48% 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
2,557
Cooling degree days, base 65°F
2,348
Growing degree days, base 40°F
9,049
Growing degree days, base 45°F
7,419
Growing degree days, base 50°F
5,919
Growing degree days, base 55°F
4,567
Growing degree days, base 60°F
3,371

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January633358
February472494
March30023237
April11969407
May20231676
June0438888
July05601,024
August05531,018
September5340786
October106106468
November34117186
December562479

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 17.4 km from Cass County. 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 USC00410408 (Atlanta). Public domain.