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Juneau, Alaska climate

Cfb Oceanic / temperate

Juneau has a seasonal cold-temperate climate (Oceanic / temperate, Köppen Cfb). The hottest month is July with an average daily high near 18°C, while the coldest is January averaging around −5°C at night. Around 1702 mm of precipitation falls each year, peaking in September (232 mm) and easing off in April (88 mm). Snowfall is heavy (223 cm of snow per year on average). At latitude 58°N, day length swings from 6.1 hours in midwinter to 17.9 hours at midsummer.

☀️ Summers
Cool
Highs near 18°C in July.
❄️ Winters
Cold
Lows near −5°C in January.
🌧️ Rain & snow
Very wet
About 1702 mm of rain a year, plus 223 cm of snow.
Snow falls through the winter months
⛅ Sky & trend
Often grey
Overcast skies dominate much of the year.

Temperature & precipitation

Daily high–low temperature range with the monthly average, plus monthly precipitation split into rain and snow · 1991–2020 normals · hover a month for the exact figures TEMPERATURE °C -10°0°10°20° PRECIPITATION (mm) 0120240 RainSnow JanAprJulOct

Hours of sunshine per day

Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER) 0h2h3h4h6h J: ~1.6 hours of sun/dayF: ~2.5 hours of sun/dayM: ~3.3 hours of sun/dayA: ~4.1 hours of sun/dayM: ~4.8 hours of sun/dayJ: ~4.4 hours of sun/dayJ: ~4.2 hours of sun/dayA: ~3.9 hours of sun/dayS: ~2.9 hours of sun/dayO: ~2.3 hours of sun/dayN: ~1.8 hours of sun/dayD: ~1.4 hours of sun/day JFMAMJJASOND Sun hours per day (est.)

Juneau climate normals (1991–2020)

JanFebMarAprMayJunJulAugSepOctNovDec
Avg high (°C)12491417181713942
Avg temp (°C)−2−11591314131061−1
Avg low (°C)−5−4−3158101073−2−3
Precipitation (mm)15310993888997131163232214166166
Snowfall (cm)6242313—————23546
Jan – JunJanFebMarAprMayJun
Avg high (°C)12491417
Avg temp (°C)−2−115913
Avg low (°C)−5−4−3158
Precipitation (mm)15310993888997
Snowfall (cm)6242313——
Jul – DecJulAugSepOctNovDec
Avg high (°C)181713942
Avg temp (°C)14131061−1
Avg low (°C)101073−2−3
Precipitation (mm)131163232214166166
Snowfall (cm)———23546

Sky & atmosphere

JanFebMarAprMayJunJulAugSepOctNovDec
Cloud cover (%)767272717176767477767577
Relative humidity (%)959392898786888990929596
Wind speed (mph)7.86.86.64.23.43.23.33.64.55.47.07.5
Jan – JunJanFebMarAprMayJun
Cloud cover (%)767272717176
Relative humidity (%)959392898786
Wind speed (mph)7.86.86.64.23.43.2
Jul – DecJulAugSepOctNovDec
Cloud cover (%)767477767577
Relative humidity (%)888990929596
Wind speed (mph)3.33.64.55.47.07.5

30-year delta table (1991–2020 minus 1981–2010, °F)

JanFebMarAprMayJunJulAugSepOctNovDec
Δ Max temp+0.3+0.5-0.4+0.3+1.0+0.2+0.1+0.2+0.4+0.3+0.5+0.6
Δ Avg temp+0.2+0.0-0.9+0.0+0.4+0.0+0.1+0.1+0.1-0.2+0.4+0.4
Δ Min temp+0.1-0.4-1.4-0.4-0.3-0.1+0.1+0.1-0.3-0.7+0.1+0.3
Jan – JunJanFebMarAprMayJun
Δ Max temp+0.3+0.5-0.4+0.3+1.0+0.2
Δ Avg temp+0.2+0.0-0.9+0.0+0.4+0.0
Δ Min temp+0.1-0.4-1.4-0.4-0.3-0.1
Jul – DecJulAugSepOctNovDec
Δ Max temp+0.1+0.2+0.4+0.3+0.5+0.6
Δ Avg temp+0.1+0.1+0.1-0.2+0.4+0.4
Δ Min temp+0.1+0.1-0.3-0.7+0.1+0.3
Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Juneau AP (NOAA GHCN station USW00025309), about 10 km from the city centre.

Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.

How we build these numbers →