Lake Marcel-Stillwater climate

Lake Marcel-Stillwater Frost Dates and Growing Season

NOAA 1991-2020 normals for Tolt S Fk Rsvr, 16.8 km from Lake Marcel-Stillwater, elevation 2000 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tolt S Fk Rsvr. 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 13 and the first fall freeze around November 10, a growing season of about 210 days.

Median at 36°F
last May 3, first October 24
Median at 32°F
last April 13, first November 10
Median at 28°F
last March 14, first November 28

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 21May 15May 11May 7May 3Apr 30Apr 27Apr 23Apr 17
32°FMay 4Apr 29Apr 23Apr 18Apr 13Apr 7Apr 3Mar 31Mar 23
28°FApr 6Mar 29Mar 23Mar 18Mar 14Mar 9Mar 4Feb 26Feb 16
24°FMar 11Mar 1Feb 23Feb 16Feb 6Jan 27Jan 13Jan 3Dec 20
20°FFeb 22Feb 13Jan 31Jan 18Jan 7Dec 31Dec 22Dec 11Dec 2
16°FFeb 16Jan 29Jan 10Jan 1Dec 24Dec 17Dec 9Dec 5Nov 27

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 15Oct 18Oct 21Oct 24Oct 26Oct 30Nov 3Nov 9
32°FOct 24Oct 30Nov 2Nov 7Nov 10Nov 14Nov 17Nov 22Nov 28
28°FNov 7Nov 13Nov 18Nov 23Nov 28Dec 2Dec 7Dec 14Dec 23
24°FNov 22Nov 28Dec 3Dec 9Dec 16Dec 24Jan 1Jan 13Feb 2
20°FNov 25Dec 2Dec 8Dec 16Dec 24Dec 31Jan 7Jan 23Feb 13
16°FNov 24Dec 1Dec 6Dec 11Dec 18Dec 26Jan 1Jan 21Feb 5

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°F196188182177172168164158149
32°F239230222216210205198192184
28°F300284274267261254246238228
24°F361349334325316306297287275
20°F365365365365355342333323310
16°F365365365365365365365350334

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
92% of years
20°F or colder
59% of years
16°F or colder
27% 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
6,287
Cooling degree days, base 65°F
136
Growing degree days, base 40°F
3,500
Growing degree days, base 45°F
2,361
Growing degree days, base 50°F
1,484
Growing degree days, base 55°F
823
Growing degree days, base 60°F
381

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January87100
February76301
March78403
April614028
May4042125
June26717212
July11951397
August11152406
September22114250
October504057
November72605
December90400

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 16.8 km from Lake Marcel-Stillwater. 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 USC00458508 (Tolt S Fk Rsvr). Public domain.