Mulino climate

Mulino Frost Dates and Growing Season

NOAA 1991-2020 normals for Molalla 7NE, 7.7 km from Mulino, elevation 647 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Molalla 7NE. 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 16 and the first fall freeze around November 19, a growing season of about 247 days.

Median at 36°F
last April 15, first November 1
Median at 32°F
last March 16, first November 19
Median at 28°F
last February 14, first December 6

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 4Apr 30Apr 26Apr 20Apr 15Apr 10Apr 5Apr 1Mar 26
32°FApr 12Apr 1Mar 27Mar 21Mar 16Mar 12Mar 7Mar 2Feb 24
28°FMar 10Mar 2Feb 26Feb 20Feb 14Feb 6Jan 29Jan 17Jan 2
24°FFeb 20Feb 9Feb 1Jan 22Jan 10Jan 3Dec 28Dec 17Dec 6
20°FFeb 15Feb 1Jan 19Jan 6Dec 31Dec 24Dec 17Dec 11Dec 3
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 16Oct 22Oct 26Oct 29Nov 1Nov 4Nov 8Nov 12Nov 19
32°FOct 31Nov 7Nov 11Nov 14Nov 19Nov 23Nov 28Dec 2Dec 9
28°FNov 13Nov 20Nov 26Dec 1Dec 6Dec 12Dec 19Dec 28Jan 12
24°FNov 23Dec 1Dec 7Dec 12Dec 19Dec 28Jan 3Jan 14Feb 2
20°FNov 30Dec 7Dec 12Dec 18Dec 25Dec 31Jan 8Jan 26Feb 11
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°F227217210204199194189183175
32°F279267259252247240233225214
28°F339325315305297289281272261
24°F365365363354344338330318306
20°F365365365365365365362348334
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
98% of years
24°F or colder
72% of years
20°F or colder
34% of years
16°F or colder
7% 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
4,451
Cooling degree days, base 65°F
390
Growing degree days, base 40°F
5,243
Growing degree days, base 45°F
3,733
Growing degree days, base 50°F
2,499
Growing degree days, base 55°F
1,559
Growing degree days, base 60°F
862

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January73206
February59209
March550033
April411390
May25415232
June13434350
July26124563
August17148597
September9061422
October3234165
November566028
December75606

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 7.7 km from Mulino. 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 USC00355681 (Molalla 7NE). Public domain.