Merlin climate

Merlin Frost Dates and Growing Season

NOAA 1991-2020 normals for Grants Pass, 13.1 km from Merlin, elevation 932 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Grants Pass. 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 8 and the first fall freeze around October 28, a growing season of about 201 days.

Median at 36°F
last May 2, first October 11
Median at 32°F
last April 8, first October 28
Median at 28°F
last March 8, first November 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°FMay 30May 20May 13May 6May 2Apr 30Apr 26Apr 20Apr 14
32°FMay 1Apr 24Apr 19Apr 13Apr 8Apr 3Mar 31Mar 26Mar 15
28°FApr 5Mar 29Mar 23Mar 16Mar 8Feb 28Feb 22Feb 14Jan 19
24°FMar 8Feb 28Feb 20Feb 12Jan 29Jan 16Jan 3Dec 23Dec 6
20°FFeb 20Jan 28Jan 16Jan 5Dec 31Dec 24Dec 15Dec 10Dec 1
16°FJan 16Jan 5Dec 31Dec 26Dec 24Dec 15Dec 13Dec 11Dec 7

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 23Sep 30Oct 3Oct 7Oct 11Oct 15Oct 19Oct 24Oct 31
32°FOct 8Oct 15Oct 19Oct 23Oct 28Nov 1Nov 6Nov 13Nov 24
28°FOct 22Oct 28Nov 2Nov 9Nov 16Nov 25Dec 2Dec 11Dec 27
24°FNov 3Nov 16Nov 28Dec 3Dec 11Dec 21Jan 2Jan 14Feb 6
20°FNov 19Dec 1Dec 7Dec 12Dec 20Dec 28Jan 5Jan 17Feb 6
16°FDec 3Dec 8Dec 10Dec 13Dec 20Dec 23Dec 30Jan 4Jan 15

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°F187178170165160155149142132
32°F234223215208201195189182172
28°F307289276266255246239225213
24°F365357344334323314304291275
20°F365365365365365365355344329
16°F365365365365365365365365359

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
83% of years
20°F or colder
40% of years
16°F or colder
11% 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
4,176
Cooling degree days, base 65°F
765
Growing degree days, base 40°F
5,855
Growing degree days, base 45°F
4,348
Growing degree days, base 50°F
3,106
Growing degree days, base 55°F
2,117
Growing degree days, base 60°F
1,350

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January73004
February567014
March519045
April3753120
May19536312
June75101476
July9269725
August9250705
September67100483
October3026188
November566029
December76305

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 13.1 km from Merlin. 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 USC00353445 (Grants Pass). Public domain.