Utqiagvik Frost Dates and Growing Season

NOAA 1991-2020 normals for Barrow Post Rogers AP, 0.9 km from Utqiagvik, elevation 31 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Barrow Post Rogers AP. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

NOAA does not state freeze dates for this station.

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	–	–	–	–	–	–	–	–	–
32°F	–	–	–	–	–	–	–	–	–
28°F	–	–	–	–	–	–	–	–	–
24°F	Jun 10	Jun 7	Jun 5	Jun 4	Jun 3	Jun 1	May 31	May 27	May 22
20°F	Jun 4	Jun 2	May 31	May 28	May 25	May 23	May 21	May 18	May 14
16°F	Jun 1	May 27	May 23	May 21	May 19	May 16	May 14	May 12	May 9

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	–	–	–	–	–	–	–	–	–
32°F	–	–	–	–	–	–	–	–	–
28°F	–	–	–	–	–	–	–	–	–
24°F	Sep 1	Sep 13	Sep 19	Sep 23	Sep 25	Sep 28	Oct 1	Oct 4	Oct 8
20°F	Sep 20	Sep 25	Sep 28	Oct 1	Oct 3	Oct 5	Oct 8	Oct 11	Oct 15
16°F	Sep 25	Sep 30	Oct 2	Oct 5	Oct 9	Oct 12	Oct 14	Oct 18	Oct 22

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	19	15	12	11	10	8	7	5	4
32°F	53	42	36	31	26	21	18	15	12
28°F	100	90	82	74	65	57	50	43	34
24°F	130	124	120	117	114	110	106	97	86
20°F	146	141	136	133	130	126	123	118	113
16°F	159	154	149	146	142	138	135	130	125

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: 18,666
Cooling degree days, base 65°F: 0
Growing degree days, base 40°F: 214
Growing degree days, base 45°F: 72
Growing degree days, base 50°F: 17
Growing degree days, base 55°F: 2
Growing degree days, base 60°F: 0

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Growing DD 50
January	2,372	0
February	2,153	0
March	2,340	0
April	1,828	0
May	1,311	0
June	870	2
July	724	10
August	781	6
September	939	0
October	1,358	0
November	1,779	0
December	2,210	0

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 0.9 km from Utqiagvik. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00027502 (Barrow Post Rogers AP). Public domain.