Filer climate

Filer Frost Dates and Growing Season

NOAA 1991-2020 normals for Buhl #2, 11.7 km from Filer, elevation 3800 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Buhl #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 25 and the first fall freeze around October 15, a growing season of about 172 days.

Median at 36°F
last May 10, first October 2
Median at 32°F
last April 25, first October 15
Median at 28°F
last April 6, first October 26

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 5May 26May 18May 14May 10May 7May 4May 1Apr 28
32°FMay 10May 4May 1Apr 29Apr 25Apr 22Apr 18Apr 14Apr 8
28°FApr 25Apr 19Apr 14Apr 10Apr 6Apr 2Mar 30Mar 25Mar 13
24°FApr 6Mar 30Mar 23Mar 16Mar 11Mar 8Mar 5Mar 2Feb 25
20°FMar 13Mar 7Mar 5Mar 2Feb 28Feb 24Feb 20Feb 16Feb 10
16°FMar 4Feb 28Feb 25Feb 20Feb 16Feb 12Feb 8Feb 3Jan 21

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 23Sep 26Sep 29Oct 2Oct 6Oct 9Oct 12Oct 17
32°FSep 29Oct 5Oct 9Oct 12Oct 15Oct 18Oct 20Oct 24Oct 29
28°FOct 13Oct 18Oct 21Oct 23Oct 26Oct 30Nov 1Nov 7Nov 12
24°FOct 22Oct 28Oct 31Nov 4Nov 7Nov 10Nov 14Nov 18Nov 22
20°FOct 31Nov 6Nov 11Nov 14Nov 18Nov 21Nov 24Nov 27Dec 1
16°FNov 7Nov 13Nov 18Nov 23Nov 26Nov 29Dec 3Dec 9Dec 18

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°F166158152148143138133126118
32°F193186181177172169163157150
28°F229218212208203198193185177
24°F261253246241236231224217209
20°F287279273267262257252245237
16°F316304297291284279272265256

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
6,093
Cooling degree days, base 65°F
720
Growing degree days, base 40°F
4,841
Growing degree days, base 45°F
3,691
Growing degree days, base 50°F
2,719
Growing degree days, base 55°F
1,911
Growing degree days, base 60°F
1,247

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11100
February88200
March701017
April507268
May27322240
June9488446
July11291745
August15249699
September12966393
October4603105
November81607
December1,09400

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 11.7 km from Filer. 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 USC00101220 (Buhl #2). Public domain.