Briscoe County climate

Briscoe County Frost Dates and Growing Season

NOAA 1991-2020 normals for Silverton, 10.6 km from Briscoe County, elevation 3280 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Silverton. 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 13 and the first fall freeze around October 28, a growing season of about 197 days.

Median at 36°F
last April 22, first October 19
Median at 32°F
last April 13, first October 28
Median at 28°F
last April 3, first November 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°FMay 5May 1Apr 29Apr 26Apr 22Apr 20Apr 17Apr 13Apr 9
32°FApr 28Apr 23Apr 20Apr 17Apr 13Apr 10Apr 7Apr 2Mar 28
28°FApr 20Apr 13Apr 9Apr 6Apr 3Mar 31Mar 25Mar 20Mar 11
24°FApr 8Apr 3Mar 30Mar 24Mar 19Mar 13Mar 9Mar 4Feb 28
20°FMar 29Mar 20Mar 14Mar 8Mar 5Mar 1Feb 26Feb 21Feb 15
16°FMar 14Mar 7Mar 2Feb 26Feb 21Feb 17Feb 12Feb 4Jan 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 6Oct 11Oct 14Oct 17Oct 19Oct 21Oct 24Oct 27Nov 1
32°FOct 14Oct 19Oct 23Oct 25Oct 28Oct 31Nov 2Nov 5Nov 8
28°FOct 23Oct 28Nov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 19
24°FNov 2Nov 6Nov 10Nov 13Nov 16Nov 19Nov 22Nov 25Dec 1
20°FNov 9Nov 14Nov 19Nov 22Nov 25Nov 28Dec 1Dec 5Dec 11
16°FNov 17Nov 24Nov 29Dec 1Dec 6Dec 11Dec 16Dec 22Dec 28

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°F196190185181178175171167160
32°F217211206201197193189184177
28°F243234227222217212207201193
24°F266258252246241236230224216
20°F289282276270265259254247237
16°F320308301295288283276269260

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
3,890
Cooling degree days, base 65°F
1,573
Growing degree days, base 40°F
7,270
Growing degree days, base 45°F
5,815
Growing degree days, base 50°F
4,514
Growing degree days, base 55°F
3,379
Growing degree days, base 60°F
2,403

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January83909
February660028
March4875113
April25325258
May79135524
June4327774
July0442907
August1401865
September32199618
October21038320
November519286
December807013

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 10.6 km from Briscoe County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00418323 (Silverton). Public domain.