Florence climate

Florence Frost Dates and Growing Season

NOAA 1991-2020 normals for Florence #2, 2.4 km from Florence, elevation 75 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Florence #2. 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 April 10 and the first fall freeze around November 15, a growing season of about 220 days.

Median at 36°F
last May 8, first October 15
Median at 32°F
last April 10, first November 15
Median at 28°F
last February 26, first December 12

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°FMay 30May 23May 17May 13May 8May 4Apr 30Apr 26Apr 18
32°FMay 5Apr 29Apr 22Apr 16Apr 10Apr 3Mar 29Mar 20Mar 6
28°FApr 1Mar 24Mar 14Mar 5Feb 26Feb 19Feb 12Jan 27Dec 25
24°FMar 13Feb 24Feb 16Feb 3Jan 12Dec 27Dec 20Dec 12Dec 4
20°FMar 23Mar 17Feb 18Dec 31Dec 24Dec 22Dec 18Dec 15Dec 8
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°FSep 17Sep 27Oct 3Oct 10Oct 15Oct 21Oct 26Oct 31Nov 9
32°FOct 23Oct 31Nov 6Nov 10Nov 15Nov 22Nov 29Dec 4Dec 13
28°FNov 12Nov 23Dec 1Dec 6Dec 12Dec 21Jan 3Jan 29Feb 17
24°FNov 29Dec 6Dec 12Dec 17Dec 23Jan 9Feb 5Feb 16Mar 1
20°FDec 8Dec 14Dec 16Dec 20Dec 22Dec 25Feb 10Mar 1Mar 21
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°F190179173166159152145136123
32°F263248237229220213205197185
28°F357331317306294283274262248
24°F365365365365365360342329311
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
100% of years
28°F or colder
93% of years
24°F or colder
41% of years
20°F or colder
11% of years
16°F or colder
4% 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
5,366
Cooling degree days, base 65°F
4
Growing degree days, base 40°F
3,844
Growing degree days, base 45°F
2,291
Growing degree days, base 50°F
1,122
Growing degree days, base 55°F
382
Growing degree days, base 60°F
58

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January65405
February58406
March598011
April521020
May409078
June3020150
July1960270
August2071259
September2602194
October3930100
November545025
December69904

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 2.4 km from Florence. 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 USC00352973 (Florence #2). Public domain.