Hamlin County climate

Hamlin County Frost Dates and Growing Season

NOAA 1991-2020 normals for Castlewood #2, 13.9 km from Hamlin County, elevation 1689 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Castlewood #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 May 6 and the first fall freeze around October 1, a growing season of about 145 days.

Median at 36°F
last May 16, first September 23
Median at 32°F
last May 6, first October 1
Median at 28°F
last April 29, first October 11

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 26May 22May 19May 16May 14May 11May 7May 3
32°FMay 20May 15May 12May 9May 6May 5May 2Apr 29Apr 25
28°FMay 11May 6May 3Apr 30Apr 29Apr 26Apr 23Apr 19Apr 14
24°FMay 3Apr 29Apr 25Apr 22Apr 19Apr 16Apr 13Apr 9Apr 5
20°FApr 27Apr 21Apr 17Apr 13Apr 10Apr 7Apr 4Apr 2Mar 27
16°FApr 19Apr 13Apr 8Apr 5Apr 2Mar 31Mar 28Mar 23Mar 16

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 10Sep 15Sep 18Sep 20Sep 23Sep 26Sep 28Oct 1Oct 5
32°FSep 19Sep 23Sep 26Sep 29Oct 1Oct 4Oct 6Oct 10Oct 14
28°FSep 27Oct 1Oct 5Oct 7Oct 11Oct 13Oct 17Oct 20Oct 24
24°FOct 5Oct 11Oct 15Oct 18Oct 21Oct 23Oct 27Oct 30Nov 2
20°FOct 16Oct 20Oct 24Oct 27Oct 30Nov 1Nov 3Nov 6Nov 11
16°FOct 24Oct 29Nov 1Nov 3Nov 6Nov 8Nov 11Nov 15Nov 20

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°F144138134130127124120115109
32°F163157152148145142138133126
28°F182176171167164160156152145
24°F202195190186182178174169163
20°F219213208203200196192187180
16°F238231225221217213208203196

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
8,568
Cooling degree days, base 65°F
484
Growing degree days, base 40°F
4,173
Growing degree days, base 45°F
3,204
Growing degree days, base 50°F
2,344
Growing degree days, base 55°F
1,599
Growing degree days, base 60°F
967

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,64200
February1,37000
March1,14019
April695143
May31620224
June6591476
July18188635
August38140567
September19743314
October599272
November1,02505
December1,46300

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 13.9 km from Hamlin County. 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 USC00391520 (Castlewood #2). Public domain.