Mossyrock climate

Mossyrock Frost Dates and Growing Season

NOAA 1991-2020 normals for Mayfield Pwr Plt, 8.8 km from Mossyrock, elevation 280 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mayfield Pwr Plt. 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 7 and the first fall freeze around November 13, a growing season of about 215 days.

Median at 36°F
last May 6, first October 24
Median at 32°F
last April 7, first November 13
Median at 28°F
last March 6, first December 1

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 23May 17May 14May 10May 6May 2Apr 28Apr 24Apr 17
32°FMay 8Apr 30Apr 24Apr 15Apr 7Apr 2Mar 29Mar 24Mar 16
28°FApr 2Mar 24Mar 19Mar 13Mar 6Feb 28Feb 24Feb 16Jan 31
24°FMar 1Feb 24Feb 16Feb 8Jan 31Jan 18Jan 7Dec 31Dec 12
20°FFeb 17Feb 8Jan 30Jan 19Jan 4Dec 30Dec 21Dec 13Dec 5
16°FFeb 9Feb 2Jan 16Jan 3Dec 31Dec 22Dec 15Dec 9Dec 3

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 4Oct 12Oct 17Oct 20Oct 24Oct 27Oct 30Nov 4Nov 11
32°FOct 24Oct 30Nov 5Nov 9Nov 13Nov 17Nov 22Nov 27Dec 4
28°FNov 8Nov 16Nov 23Nov 27Dec 1Dec 5Dec 13Dec 20Jan 1
24°FNov 23Nov 30Dec 5Dec 11Dec 19Dec 25Jan 2Jan 20Feb 7
20°FNov 30Dec 5Dec 10Dec 17Dec 25Jan 1Jan 13Jan 29Feb 11
16°FDec 2Dec 7Dec 11Dec 18Dec 24Jan 1Jan 12Jan 30Feb 6

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°F197189182177171166160154144
32°F249238229222215208201193181
28°F311296286278269261254246232
24°F365359346336328320311302285
20°F365365365365365363351337325
16°F365365365365365365365365362

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
85% of years
20°F or colder
43% of years
16°F or colder
14% 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
5,086
Cooling degree days, base 65°F
237
Growing degree days, base 40°F
4,533
Growing degree days, base 45°F
3,146
Growing degree days, base 50°F
2,054
Growing degree days, base 55°F
1,226
Growing degree days, base 60°F
619

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January80500
February66201
March631012
April471262
May28410209
June17526303
July4988504
August4386508
September13925337
October3981104
November623012
December80702

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 8.8 km from Mossyrock. 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 USC00455110 (Mayfield Pwr Plt). Public domain.