Girdwood, Alaska – A Climate Profile

Photo Credit: Girdwood Community Garden Facebook Page.


Girdwood is a small community located 48 miles southeast of downtown Anchorage. Because Girdwood is located in a temperate rainforest, its summers are often overcast, cool and the ground is wet year round. The annual temperature usually varies between 16 to 64 °F but sometimes dip below -9 °F or rise above 72 °F. The record low was -30 °F (January 1989) and the record high was 88 °F (July 1972). A gardener can expect a typical growing season of approximately 4 to 4.5 months. In a really exceptional year the growing season could be as long as 5 months or as short as 3.5 months.

The important statistic for any gardener to bear in mind is how many ideal growing days does (s)he have. An ideal temperature for most crops for photosynthesis is 50 to 86 °F. The number of days (and hours of the day) which fall into ideal for growing vary widely from year to year in Girdwood. And this can present a challenge to those wanting to grow a successful garden and reap a reliable harvest.

Another problem that the gardener must solve in a temperate rainforest such as Girdwood is the soggy, cold soil. Plants thrive only when both the soil moisture and temperature suit the particular cultivar. And not many vegetable crops like cold, soggy soil. Your garden probably won’t be happy in those conditions, and yields will be low, if any.

On the other hand, Girdwood gardeners benefit from a reliable source of water and relatively mild temperatures. So, with proper growing strategies (e.g., raised beds, soil heating cables, greenhouses, high/low tunnels, IRT mulch, southern aspect) all of the problems associated with wet and cold conditions can be overcome, and gardens can thrive and produce an abundant yield.

The following climate table is relevant to the community of Girdwood.

Climate Information Table

Link to the nearest weather station:  Name ALYESKA, AK US  ID GHCND:USC00500243  Lat/Lon 60.9583, -149.1108

Normals for years: 1981-2010

USDA Plant Hardiness  Zone:   Zone 4b: -25 °F to -20 °F

May June July August September
Average Daily Temperature ( °F) 45.3 53.0 56.9 55.0 47.5
Average Daily Maximum ( °F) 54.3 62.2 65.1 63.2 55.1
Average Daily Minimum ( °F) 36.2 43.7 48.7 46.7 39.8
Average rainfall (in.) 3.4 2.3 2.6 4.8 7.8
32 °F is used here to determine frosts. Probable Growing Season (90% probability) Possible Growing Season (10% probability)
Date of First frost 10/9 9/10
Date of Last frost 4/30 5/25
Freeze Free Period 115 154
When daylengths are longer than 12 hours 3/17 9/25

In full disclosure I’m currently not residing in Girdwood. I’m no longer a full-time resident of Alaska, and I relinquished my Alaskan residency so I could spend my winters growing things in Texas. I used to live in Girdwood, so I do understand the significant challenges which have to be overcome by the home gardener. My number one recommendation for those who are really serious about growing a successful garden in Girdwood is to create an artificial microclimate that regulates heat and moisture. Said microclimate doesn’t have to necessarily be an expensive greenhouse, but it does have to somehow alter the natural climate of a temperate rainforest.

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