Tieton climate

Tieton Frost Dates and Growing Season

NOAA 1991-2020 normals for Yakima Air Terminal, 22 km from Tieton, elevation 1064 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Yakima Air Terminal. 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 8 and the first fall freeze around October 4, a growing season of about 149 days.

Median at 36°F
last May 29, first September 23
Median at 32°F
last May 8, first October 4
Median at 28°F
last April 23, first October 16

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 16Jun 8Jun 4Jun 1May 29May 24May 20May 15May 9
32°FMay 27May 20May 15May 10May 8May 4Apr 30Apr 28Apr 24
28°FMay 8May 3Apr 30Apr 26Apr 23Apr 20Apr 16Apr 12Apr 6
24°FApr 22Apr 17Apr 11Apr 5Apr 2Mar 30Mar 24Mar 16Mar 8
20°FApr 3Mar 25Mar 16Mar 10Mar 5Mar 1Feb 25Feb 19Feb 9
16°FMar 7Feb 28Feb 24Feb 19Feb 14Feb 8Feb 2Jan 25Jan 10

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 8Sep 12Sep 17Sep 20Sep 23Sep 26Sep 29Oct 1Oct 5
32°FSep 23Sep 27Sep 30Oct 2Oct 4Oct 6Oct 9Oct 13Oct 17
28°FOct 2Oct 6Oct 9Oct 13Oct 16Oct 19Oct 22Oct 26Nov 1
24°FOct 13Oct 18Oct 22Oct 25Oct 28Oct 31Nov 1Nov 6Nov 12
20°FOct 21Oct 28Nov 1Nov 5Nov 8Nov 12Nov 17Nov 22Nov 29
16°FNov 1Nov 8Nov 13Nov 17Nov 21Nov 25Nov 30Dec 5Dec 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°F13913212612211711210710092
32°F170162157153149145140134126
28°F199191185179175171167161155
24°F238227221214209205199194183
20°F280268260253247241235227215
16°F321309299292285277270262251

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
5,756
Cooling degree days, base 65°F
606
Growing degree days, base 40°F
4,840
Growing degree days, base 45°F
3,640
Growing degree days, base 50°F
2,628
Growing degree days, base 55°F
1,791
Growing degree days, base 60°F
1,117

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,03100
February79401
March670012
April452177
May21927283
June8285453
July14244696
August19202648
September13146367
October471186
November80906
December1,06500

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 22 km from Tieton. 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 USW00024243 (Yakima Air Terminal). Public domain.