Valdez climate

Valdez Frost Dates and Growing Season

NOAA 1991-2020 normals for Valdez WSO, 0.2 km from Valdez, elevation 95 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Valdez WSO. 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 30 and the first fall freeze around October 2, a growing season of about 157 days.

Median at 36°F
last May 15, first September 20
Median at 32°F
last April 30, first October 2
Median at 28°F
last April 14, first October 20

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 27May 24May 20May 17May 15May 12May 9May 6May 2
32°FMay 10May 6May 3May 1Apr 30Apr 27Apr 24Apr 21Apr 17
28°FApr 26Apr 22Apr 19Apr 17Apr 14Apr 12Apr 10Apr 8Apr 4
24°FApr 19Apr 14Apr 10Apr 7Apr 5Apr 3Apr 2Mar 31Mar 25
20°FApr 9Apr 5Apr 2Mar 31Mar 28Mar 25Mar 22Mar 18Mar 13
16°FApr 3Mar 29Mar 25Mar 22Mar 18Mar 15Mar 11Mar 7Feb 28

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 6Sep 11Sep 15Sep 17Sep 20Sep 22Sep 25Sep 27Oct 1
32°FSep 20Sep 25Sep 28Oct 1Oct 2Oct 5Oct 9Oct 14Oct 19
28°FOct 2Oct 7Oct 12Oct 16Oct 20Oct 23Oct 26Oct 30Nov 4
24°FOct 15Oct 21Oct 25Oct 29Nov 1Nov 3Nov 6Nov 11Nov 16
20°FOct 27Nov 1Nov 4Nov 7Nov 11Nov 15Nov 18Nov 22Nov 28
16°FNov 3Nov 8Nov 14Nov 17Nov 21Nov 24Nov 29Dec 3Dec 13

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°F143138134130127124120116111
32°F177170165161157153149144138
28°F206200196192188184180175169
24°F227221216212209205201197189
20°F252242236231227223219213206
16°F278267258251247241235230222

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
100% of years
20°F or colder
100% of years
16°F or colder
100% 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
9,219
Cooling degree days, base 65°F
3
Growing degree days, base 40°F
1,995
Growing degree days, base 45°F
1,171
Growing degree days, base 50°F
537
Growing degree days, base 55°F
158
Growing degree days, base 60°F
25

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27400
February1,07400
March1,09000
April77601
May536028
June3191139
July2622205
August3270141
September501022
October79101
November1,06800
December1,20100

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 0.2 km from Valdez. 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 USW00026442 (Valdez WSO). Public domain.