Green climate

Green Frost Dates and Growing Season

NOAA 1991-2020 normals for Roseburg Kqen, 5.9 km from Green, elevation 425 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Roseburg Kqen. 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 March 23 and the first fall freeze around November 18, a growing season of about 237 days.

Median at 36°F
last April 21, first October 25
Median at 32°F
last March 23, first November 18
Median at 28°F
last February 20, first December 11

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 9May 3Apr 29Apr 25Apr 21Apr 17Apr 12Apr 8Mar 31
32°FApr 16Apr 7Apr 1Mar 28Mar 23Mar 19Mar 13Mar 4Feb 25
28°FMar 21Mar 10Mar 1Feb 25Feb 20Feb 11Feb 1Jan 20Dec 31
24°FFeb 26Feb 17Feb 8Jan 26Jan 11Jan 3Dec 27Dec 19Dec 6
20°FFeb 19Jan 25Jan 9Jan 1Dec 30Dec 25Dec 22Dec 17Dec 9
16°F–––––––––

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 8Oct 14Oct 18Oct 21Oct 25Oct 29Nov 1Nov 8Nov 17
32°FOct 24Oct 31Nov 5Nov 11Nov 18Nov 24Nov 30Dec 6Dec 17
28°FNov 8Nov 18Nov 28Dec 3Dec 11Dec 19Dec 26Jan 7Jan 31
24°FNov 27Dec 5Dec 13Dec 21Dec 27Jan 2Jan 11Feb 1Feb 15
20°FDec 7Dec 13Dec 20Dec 22Dec 27Dec 31Jan 5Jan 21Feb 15
16°F–––––––––

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°F218208200193188182176170161
32°F278266255246237229222215203
28°F345328316307299289279268253
24°F365365365365362350336321308
20°F365365365365365365365365352
16°F365365365365365365365365365

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
95% of years
24°F or colder
56% of years
20°F or colder
17% of years
16°F or colder
4% 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
3,809
Cooling degree days, base 65°F
690
Growing degree days, base 40°F
6,088
Growing degree days, base 45°F
4,489
Growing degree days, base 50°F
3,155
Growing degree days, base 55°F
2,105
Growing degree days, base 60°F
1,294

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January667010
February533020
March487060
April3534131
May18432316
June6883465
July8235693
August6226685
September54100497
October2679218
November498049
December685012

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 5.9 km from Green. 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 USC00357331 (Roseburg Kqen). Public domain.