Holt County climate

Holt County Frost Dates and Growing Season

NOAA 1991-2020 normals for Oregon, 13.9 km from Holt County, elevation 1058 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Oregon. 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 16 and the first fall freeze around October 20, a growing season of about 186 days.

Median at 36°F
last April 26, first October 10
Median at 32°F
last April 16, first October 20
Median at 28°F
last April 6, first October 30

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 7May 4May 1Apr 29Apr 26Apr 23Apr 19Apr 16Apr 10
32°FApr 30Apr 25Apr 21Apr 18Apr 16Apr 12Apr 9Apr 6Apr 2
28°FApr 21Apr 16Apr 12Apr 9Apr 6Apr 3Apr 1Mar 29Mar 23
24°FApr 12Apr 6Apr 3Mar 31Mar 29Mar 26Mar 22Mar 17Mar 11
20°FApr 3Mar 30Mar 26Mar 22Mar 18Mar 15Mar 11Mar 7Mar 2
16°FMar 26Mar 21Mar 17Mar 13Mar 9Mar 6Mar 3Feb 28Feb 22

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 25Sep 30Oct 3Oct 6Oct 10Oct 12Oct 15Oct 19Oct 22
32°FOct 3Oct 10Oct 14Oct 17Oct 20Oct 22Oct 25Oct 28Nov 1
28°FOct 14Oct 19Oct 23Oct 27Oct 30Nov 1Nov 4Nov 7Nov 12
24°FOct 22Oct 28Nov 1Nov 4Nov 6Nov 10Nov 13Nov 17Nov 24
20°FOct 31Nov 5Nov 9Nov 12Nov 15Nov 19Nov 23Nov 28Dec 3
16°FNov 8Nov 13Nov 17Nov 21Nov 25Nov 30Dec 2Dec 6Dec 12

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°F185180175171168164160155148
32°F205198194190186182178173166
28°F226218213209205200196191184
24°F246237232227223217213208199
20°F265257252246241236230225216
16°F283276270265260256250244236

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
5,662
Cooling degree days, base 65°F
1,208
Growing degree days, base 40°F
6,059
Growing degree days, base 45°F
4,834
Growing degree days, base 50°F
3,738
Growing degree days, base 55°F
2,771
Growing degree days, base 60°F
1,924

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,23101
February97308
March721356
April38916170
May13489427
June12251690
July2369832
August4320781
September77138514
October33821216
November707041
December1,07603

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 Holt 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 USC00236357 (Oregon). Public domain.