Palmer climate

Palmer Frost Dates and Growing Season

NOAA 1991-2020 normals for Lazy Mtn, 5.2 km from Palmer, elevation 733 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lazy Mtn. 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 May 22 and the first fall freeze around September 16, a growing season of about 114 days.

Median at 36°F
last June 7, first September 1
Median at 32°F
last May 22, first September 16
Median at 28°F
last May 6, first September 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°FJun 22Jun 16Jun 12Jun 10Jun 7Jun 5Jun 3Jun 1May 28
32°FJun 3May 31May 28May 25May 22May 19May 16May 13May 9
28°FMay 18May 13May 10May 8May 6May 4May 2Apr 30Apr 24
24°FMay 4Apr 30Apr 28Apr 25Apr 22Apr 20Apr 17Apr 14Apr 10
20°FApr 26Apr 21Apr 18Apr 15Apr 12Apr 10Apr 8Apr 5Apr 3
16°FApr 20Apr 14Apr 9Apr 7Apr 5Apr 4Apr 2Mar 31Mar 26

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°FAug 18Aug 24Aug 28Aug 31Sep 1Sep 4Sep 7Sep 10Sep 15
32°FSep 1Sep 6Sep 10Sep 13Sep 16Sep 18Sep 21Sep 24Sep 28
28°FSep 14Sep 20Sep 23Sep 25Sep 28Sep 30Oct 1Oct 5Oct 9
24°FSep 26Oct 1Oct 2Oct 5Oct 8Oct 10Oct 13Oct 17Oct 22
20°FOct 2Oct 7Oct 11Oct 14Oct 16Oct 19Oct 22Oct 25Oct 31
16°FOct 11Oct 16Oct 20Oct 23Oct 26Oct 28Nov 1Nov 3Nov 8

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°F1029692888581787365
32°F13212612211811411110810397
28°F161155151146143140137132127
24°F186180175171168165161157152
20°F203198193189187183179174169
16°F217212208204201197194189182

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
10,772
Cooling degree days, base 65°F
2
Growing degree days, base 40°F
1,810
Growing degree days, base 45°F
1,076
Growing degree days, base 50°F
510
Growing degree days, base 55°F
164
Growing degree days, base 60°F
28

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,52500
February1,25500
March1,28200
April88201
May580024
June3471122
July2571211
August3370139
September575014
October96301
November1,30500
December1,46600

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 5.2 km from Palmer. 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 USC00505464 (Lazy Mtn). Public domain.