Inverness climate

Inverness Frost Dates and Growing Season

NOAA 1991-2020 normals for Union Springs 9 S, 0.1 km from Inverness, elevation 440 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Union Springs 9 S. 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 25 and the first fall freeze around November 6, a growing season of about 226 days.

Median at 36°F
last April 7, first October 29
Median at 32°F
last March 25, first November 6
Median at 28°F
last March 9, first November 17

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 24Apr 19Apr 14Apr 11Apr 7Apr 4Mar 31Mar 26Mar 18
32°FApr 13Apr 6Apr 1Mar 29Mar 25Mar 21Mar 17Mar 10Feb 28
28°FMar 30Mar 24Mar 18Mar 14Mar 9Mar 4Feb 28Feb 20Feb 9
24°FMar 16Mar 8Mar 2Feb 26Feb 19Feb 12Feb 5Jan 30Jan 19
20°FMar 3Feb 25Feb 14Feb 6Feb 1Jan 29Jan 22Jan 12Dec 31
16°FFeb 21Feb 7Feb 2Jan 30Jan 24Jan 17Jan 11Jan 4Dec 26

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 15Oct 20Oct 23Oct 26Oct 29Nov 1Nov 3Nov 6Nov 11
32°FOct 24Oct 29Nov 1Nov 4Nov 6Nov 9Nov 12Nov 17Nov 25
28°FNov 1Nov 5Nov 9Nov 12Nov 17Nov 21Nov 27Dec 2Dec 11
24°FNov 10Nov 17Nov 22Nov 27Dec 2Dec 8Dec 20Jan 1Jan 9
20°FNov 23Dec 2Dec 11Dec 22Dec 30Jan 3Jan 10Jan 19Feb 1
16°FDec 11Dec 24Jan 1Jan 4Jan 9Jan 15Jan 21Jan 30Feb 6

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°F227219213209204199194190182
32°F256246237232226221217210203
28°F291278270262255249243236225
24°F331316307300292285277267256
20°F365354342334327320310302289
16°F365365365365362350340331317

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
86% of years
16°F or colder
54% 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
2,470
Cooling degree days, base 65°F
1,900
Growing degree days, base 40°F
8,659
Growing degree days, base 45°F
6,996
Growing degree days, base 50°F
5,478
Growing degree days, base 55°F
4,113
Growing degree days, base 60°F
2,918

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January584377
February4345101
March29620233
April14152368
May30182617
June0351801
July0456921
August0431896
September5293738
October11087449
November35015176
December5215102

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 Inverness. 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 USC00018438 (Union Springs 9 S). Public domain.