Estelline climate

Estelline Frost Dates and Growing Season

NOAA 1991-2020 normals for Castlewood, 19.5 km from Estelline, elevation 1685 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Castlewood. 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 10 and the first fall freeze around September 27, a growing season of about 139 days.

Median at 36°F
last May 19, first September 17
Median at 32°F
last May 10, first September 27
Median at 28°F
last May 1, first October 4

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 1May 29May 25May 22May 19May 17May 14May 12May 8
32°FMay 23May 18May 15May 12May 10May 8May 5May 2Apr 29
28°FMay 14May 10May 6May 4May 1Apr 29Apr 26Apr 22Apr 17
24°FMay 6May 1Apr 29Apr 26Apr 23Apr 19Apr 16Apr 13Apr 7
20°FApr 29Apr 23Apr 19Apr 16Apr 13Apr 10Apr 7Apr 4Mar 31
16°FApr 21Apr 15Apr 11Apr 8Apr 5Apr 3Mar 31Mar 24Mar 18

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 4Sep 9Sep 12Sep 15Sep 17Sep 20Sep 23Sep 26Sep 29
32°FSep 14Sep 18Sep 22Sep 24Sep 27Sep 29Oct 1Oct 4Oct 7
28°FSep 22Sep 26Sep 30Oct 2Oct 4Oct 7Oct 10Oct 13Oct 18
24°FSep 30Oct 4Oct 8Oct 11Oct 15Oct 18Oct 21Oct 24Oct 28
20°FOct 9Oct 15Oct 20Oct 22Oct 25Oct 27Oct 30Nov 2Nov 6
16°FOct 20Oct 26Oct 29Nov 1Nov 3Nov 5Nov 8Nov 12Nov 17

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°F138132127123120116112108101
32°F155150145142139135131126120
28°F175169164160156153148144136
24°F196188183179175171167162155
20°F214207202198194190187181174
16°F234227221216212208203198190

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
8,859
Cooling degree days, base 65°F
419
Growing degree days, base 40°F
3,923
Growing degree days, base 45°F
2,982
Growing degree days, base 50°F
2,157
Growing degree days, base 55°F
1,446
Growing degree days, base 60°F
860

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,67200
February1,39600
March1,14403
April707136
May34716195
June8985447
July28164601
August47117535
September23035279
October638258
November1,06502
December1,49600

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 19.5 km from Estelline. 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 USC00391519 (Castlewood). Public domain.