Gateway climate

Gateway Frost Dates and Growing Season

NOAA 1991-2020 normals for Matanuska Exp Farm, 1 km from Gateway, elevation 172 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Matanuska Exp Farm. 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 14 and the first fall freeze around September 20, a growing season of about 127 days.

Median at 36°F
last May 28, first September 8
Median at 32°F
last May 14, first September 20
Median at 28°F
last May 1, first October 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°FJun 6Jun 3Jun 1May 30May 28May 26May 23May 21May 17
32°FMay 26May 22May 19May 17May 14May 12May 10May 7May 3
28°FMay 13May 9May 6May 3May 1Apr 29Apr 26Apr 22Apr 17
24°FMay 1Apr 28Apr 25Apr 21Apr 18Apr 15Apr 12Apr 8Apr 5
20°FApr 23Apr 18Apr 13Apr 9Apr 7Apr 5Apr 3Apr 1Mar 28
16°FApr 18Apr 9Apr 6Apr 4Apr 2Mar 31Mar 28Mar 24Mar 17

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 27Aug 31Sep 2Sep 5Sep 8Sep 11Sep 14Sep 17Sep 20
32°FSep 6Sep 11Sep 16Sep 18Sep 20Sep 23Sep 26Sep 28Oct 1
28°FSep 18Sep 23Sep 26Sep 28Oct 1Oct 3Oct 6Oct 10Oct 15
24°FSep 28Oct 1Oct 4Oct 7Oct 10Oct 13Oct 17Oct 21Oct 25
20°FOct 4Oct 9Oct 12Oct 16Oct 19Oct 23Oct 25Oct 29Nov 2
16°FOct 11Oct 15Oct 19Oct 23Oct 26Oct 28Nov 1Nov 3Nov 9

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°F11811210910510298959185
32°F144137134130127124120115109
28°F171166161156152148144139133
24°F194188183179175171167163156
20°F211205200196193189185180174
16°F227220215210206202197192184

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
10,296
Cooling degree days, base 65°F
8
Growing degree days, base 40°F
2,227
Growing degree days, base 45°F
1,417
Growing degree days, base 50°F
766
Growing degree days, base 55°F
307
Growing degree days, base 60°F
75

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,56100
February1,25900
March1,23700
April80302
May515042
June2712187
July1835287
August2601209
September506037
October92103
November1,30200
December1,48000

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 1 km from Gateway. 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 USC00505733 (Matanuska Exp Farm). Public domain.