Pilot Rock climate

Pilot Rock Frost Dates and Growing Season

NOAA 1991-2020 normals for Pilot Rock 1 Se, 0.9 km from Pilot Rock, elevation 1720 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pilot Rock 1 Se. 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 7 and the first fall freeze around October 4, a growing season of about 147 days.

Median at 36°F
last May 30, first September 20
Median at 32°F
last May 7, first October 4
Median at 28°F
last April 21, first October 15

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 17Jun 11Jun 6Jun 2May 30May 26May 22May 17May 12
32°FMay 28May 19May 15May 11May 7May 4May 2Apr 30Apr 24
28°FMay 6May 1Apr 28Apr 24Apr 21Apr 18Apr 14Apr 9Apr 1
24°FApr 15Apr 9Apr 5Mar 31Mar 28Mar 24Mar 18Mar 11Mar 4
20°FMar 28Mar 20Mar 13Mar 8Mar 4Feb 28Feb 25Feb 19Feb 10
16°FMar 9Mar 2Feb 26Feb 22Feb 17Feb 12Feb 5Jan 26Jan 8

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 1Sep 7Sep 12Sep 16Sep 20Sep 23Sep 26Sep 30Oct 4
32°FSep 16Sep 24Sep 28Oct 1Oct 4Oct 6Oct 9Oct 12Oct 17
28°FOct 1Oct 5Oct 8Oct 12Oct 15Oct 19Oct 23Oct 27Nov 2
24°FOct 12Oct 18Oct 23Oct 26Oct 30Nov 2Nov 6Nov 12Nov 19
20°FOct 24Oct 31Nov 3Nov 9Nov 14Nov 18Nov 23Nov 29Dec 8
16°FNov 1Nov 10Nov 18Nov 24Nov 28Dec 4Dec 9Dec 17Jan 1

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°F1351281221161111061019587
32°F169161156151147143137132123
28°F202193188182177172168163154
24°F245235228222216211206198189
20°F289277268262255249242234224
16°F331315305296289281272265253

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
99% 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
5,333
Cooling degree days, base 65°F
567
Growing degree days, base 40°F
5,006
Growing degree days, base 45°F
3,684
Growing degree days, base 50°F
2,597
Growing degree days, base 55°F
1,732
Growing degree days, base 60°F
1,061

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January90405
February74506
March643021
April464168
May25517241
June10563409
July16223672
August19205651
September12354384
October4183119
November708019
December93304

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 0.9 km from Pilot Rock. 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 USC00356634 (Pilot Rock 1 Se). Public domain.