Mulga climate

Mulga Frost Dates and Growing Season

NOAA 1991-2020 normals for Bessemer 3 Wsw, 17.5 km from Mulga, elevation 445 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bessemer 3 Wsw. 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 23 and the first fall freeze around November 10, a growing season of about 231 days.

Median at 36°F
last April 6, first November 1
Median at 32°F
last March 23, first November 10
Median at 28°F
last March 9, first November 23

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 21Apr 16Apr 13Apr 9Apr 6Apr 3Mar 31Mar 27Mar 21
32°FApr 11Apr 5Mar 31Mar 27Mar 23Mar 20Mar 15Mar 9Mar 3
28°FMar 28Mar 21Mar 16Mar 13Mar 9Mar 4Feb 28Feb 24Feb 15
24°FMar 15Mar 9Mar 4Feb 28Feb 23Feb 18Feb 11Feb 3Jan 25
20°FMar 5Feb 27Feb 17Feb 12Feb 5Jan 31Jan 26Jan 19Jan 7
16°FFeb 19Feb 10Feb 2Jan 30Jan 25Jan 20Jan 13Jan 6Dec 30

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 18Oct 23Oct 26Oct 29Nov 1Nov 3Nov 5Nov 9Nov 14
32°FOct 27Nov 1Nov 3Nov 6Nov 10Nov 13Nov 17Nov 21Nov 28
28°FNov 4Nov 10Nov 15Nov 19Nov 23Nov 27Dec 1Dec 5Dec 12
24°FNov 15Nov 23Nov 29Dec 2Dec 6Dec 12Dec 23Jan 1Jan 7
20°FDec 1Dec 7Dec 16Dec 25Jan 1Jan 4Jan 10Jan 16Jan 30
16°FDec 11Dec 24Jan 1Jan 4Jan 8Jan 15Jan 20Jan 28Feb 5

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°F230222217212208204200195189
32°F256247242236231227222216208
28°F287277269262257253248241233
24°F324311303296289281274266257
20°F357345336330322314306298285
16°F365365365357348340333324311

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
92% of years
16°F or colder
65% 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
2,537
Cooling degree days, base 65°F
2,100
Growing degree days, base 40°F
8,806
Growing degree days, base 45°F
7,156
Growing degree days, base 50°F
5,646
Growing degree days, base 55°F
4,294
Growing degree days, base 60°F
3,108

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January628158
February456387
March30116221
April12061395
May21213657
June0387837
July0501966
August0485950
September6319763
October104100464
November34912168
December552379

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 17.5 km from Mulga. 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 USC00010764 (Bessemer 3 Wsw). Public domain.