Unalaska weather by month
What a typical year looks like in Unalaska, Alaska: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Dutch Harbor, 2 km from Unalaska; records cover 1915–2026.
The year at a glance
- Precipitation a year
- 60.1 in1527 mm
- Snow a year
- 82 in207 cm
- Last spring freeze
- May 8
- First fall freeze
- Oct 22
- Heating degree days
- 8,527
- Cooling degree days
- 1
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are 15°−9° (heating, 99%) and 68°20° (cooling, 1%).
Month by month
Unalaska in January
Highs average 37°3° and lows 29°−2°, with 6.8 in172 mm of precipitation and 22 in56 cm of snow in a typical January.
- Record high
- 58°14° (1952)
- Record low
- −8°−22° (1986)
- Heating degree days
- 992
- Cooling degree days
- 0
Unalaska in February
Highs average 39°4° and lows 29°−1°, with 5.2 in132 mm of precipitation and 14 in36 cm of snow in a typical February.
- Record high
- 60°16° (1932)
- Record low
- 0°−18° (1991)
- Heating degree days
- 868
- Cooling degree days
- 0
Unalaska in March
Highs average 39°4° and lows 29°−2°, with 4.7 in118 mm of precipitation and 17 in42 cm of snow in a typical March.
- Record high
- 69°21° (1936)
- Record low
- 2°−17° (1983)
- Heating degree days
- 959
- Cooling degree days
- 0
Unalaska in April
Highs average 42°5° and lows 33°0°, with 3.5 in88 mm of precipitation and 6 in16 cm of snow in a typical April.
- Record high
- 61°16° (1920)
- Record low
- 10°−12° (1983)
- Heating degree days
- 836
- Cooling degree days
- 0
Unalaska in May
Highs average 47°8° and lows 37°3°, with 4.2 in107 mm of precipitation and 0.2 in0.5 cm of snow in a typical May.
- Record high
- 66°19° (1927)
- Record low
- 15°−9° (1984)
- Heating degree days
- 712
- Cooling degree days
- 0
Unalaska in June
Highs average 52°11° and lows 42°6°, with 2.5 in64 mm of precipitation in a typical June.
- Record high
- 73°23° (1915)
- Record low
- 30°−1° (1916)
- Heating degree days
- 530
- Cooling degree days
- 0
Unalaska in July
Highs average 57°14° and lows 47°8°, with 2.3 in58 mm of precipitation in a typical July.
- Record high
- 79°26° (1917)
- Record low
- 34°1° (1989)
- Heating degree days
- 403
- Cooling degree days
- 0
Unalaska in August
Highs average 59°15° and lows 48°9°, with 2.9 in73 mm of precipitation in a typical August.
- Record high
- 82°28° (1982)
- Record low
- 25°−4° (1986)
- Heating degree days
- 351
- Cooling degree days
- 1
Unalaska in September
Highs average 55°13° and lows 44°7°, with 5.7 in146 mm of precipitation in a typical September.
- Record high
- 80°27° (1939)
- Record low
- 23°−5° (1993)
- Heating degree days
- 468
- Cooling degree days
- 0
Unalaska in OctoberThis month
Highs average 48°9° and lows 38°4°, with 7.9 in200 mm of precipitation and 0.4 in1 cm of snow in a typical October.
- Record high
- 68°20° (2025)
- Record low
- 5°−15° (1985)
- Heating degree days
- 674
- Cooling degree days
- 0
Unalaska in November
Highs average 43°6° and lows 33°1°, with 6.7 in169 mm of precipitation and 6 in16 cm of snow in a typical November.
- Record high
- 67°19° (1926)
- Record low
- 8°−13° (1991)
- Heating degree days
- 802
- Cooling degree days
- 0
Unalaska in December
Highs average 39°4° and lows 31°−1°, with 7.9 in200 mm of precipitation and 16 in40 cm of snow in a typical December.
- Record high
- 59°15° (1994)
- Record low
- 5°−15° (1983)
- Heating degree days
- 932
- Cooling degree days
- 0