Florence climate

Florence Frost Dates and Growing Season

NOAA 1991-2020 normals for Florence, 1.4 km from Florence, elevation 1300 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Florence. 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 May 24 and the first fall freeze around September 25, a growing season of about 121 days.

Median at 36°F
last June 5, first September 10
Median at 32°F
last May 24, first September 25
Median at 28°F
last May 11, first October 6

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°FJun 24Jun 17Jun 12Jun 8Jun 5Jun 2May 31May 27May 23
32°FJun 8Jun 3May 30May 27May 24May 22May 19May 15May 9
28°FMay 26May 21May 17May 14May 11May 7May 4Apr 30Apr 27
24°FMay 15May 9May 5May 1Apr 29Apr 27Apr 24Apr 20Apr 15
20°FMay 1Apr 28Apr 24Apr 21Apr 18Apr 15Apr 13Apr 10Apr 6
16°FApr 24Apr 19Apr 16Apr 13Apr 10Apr 7Apr 4Apr 2Mar 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°FAug 24Aug 30Sep 3Sep 6Sep 10Sep 13Sep 17Sep 21Sep 27
32°FSep 7Sep 13Sep 18Sep 22Sep 25Sep 29Oct 2Oct 5Oct 9
28°FSep 21Sep 27Oct 1Oct 3Oct 6Oct 9Oct 13Oct 16Oct 20
24°FOct 4Oct 10Oct 14Oct 17Oct 21Oct 25Oct 28Nov 1Nov 5
20°FOct 18Oct 26Oct 30Nov 1Nov 3Nov 5Nov 8Nov 12Nov 17
16°FNov 1Nov 4Nov 7Nov 9Nov 13Nov 15Nov 18Nov 22Nov 27

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°F115108103989388837768
32°F14513613012612111611210697
28°F168161156151146142137133125
24°F194187182178174170165160152
20°F217210206202198195190185177
16°F236229224220216212208203197

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
100% of years
20°F or colder
100% of years
16°F or colder
100% 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
9,149
Cooling degree days, base 65°F
231
Growing degree days, base 40°F
3,381
Growing degree days, base 45°F
2,489
Growing degree days, base 50°F
1,717
Growing degree days, base 55°F
1,068
Growing degree days, base 60°F
565

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,62600
February1,39700
March1,22803
April798016
May4169145
June14644353
July6495496
August9262436
September28219222
October658144
November1,02302
December1,42000

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 1.4 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 USC00472826 (Florence). Public domain.