January
Weather in January
Temperature
Seattle starts January with an average high-temperature of a still chilly 45°F (7.2°C)hinting at a minimal fluctuation from December. Night temperatures in January exhibit a subtle decreasesettling at an average of 36°F (2.2°C).Humidity
The most humid month is Januarywith an average relative humidity of 85%.Rainfall
In Seattlein Januaryduring 8.8 rainfall days0.71" (18mm) of precipitation is typically accumulated. In Seattleduring the entire yearthe rain falls for 84.2 days and collects up to 5.2" (132mm) of precipitation.Snowfall
Months with snowfall are January through March and November. January is the first month it typically snows. Throughout Januaryin the average 1.3 snowfall daysit receives 0.12" (3mm) of snow. In Seattleduring the entire yearsnow falls for 4.8 days and aggregates up to 0.94" (24mm) of snow.Ocean temperature
In Januarythe average ocean temperature is 45.5°F (7.5°C).Note: Swimming at temperatures less than 50°F (10°C) in 45.5°F (7.5°C) is feasible with the right swimsuit; if notexpect cold shock and breathlessness. A quick swim at 55.4°F (13°C) without adequate warmth can be discomforting.
Daylight
In Seattlethe average length of the day in January is 8h and 58min.On the first day of Januarysunrise is at 7:57 am and sunset at 4:28 pm. On the last day of the monthsunrise is at 7:37 am and sunset at 5:08 pm PST.
Sunshine
In Januarythe average sunshine is 4.4h.UV index
The months with the lowest UV index are JanuaryFebruaryNovember and Decemberwith an average maximum UV index of 2. A UV Index value of 2and lesssymbolizes a minimal health hazard from unprotected exposure to Sun's UV rays for average individuals.Note: The maximum daily UV index of 2 in January converts into the following recommendations:
Most people face no serious problems with extended sun exposurebut those with fair skininfantsand children always need protection. Being exposed to the midday Sun can have harmful effects due to strong UV radiation; always take precautions. Your best bet for sun defense on the faceeyesand neck is a hat with a wide brim. Remember this! The UV radiation of the Sun can be nearly doubled by the reflective properties of snow.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in January
SeattleWA
- Average high temperature in January: 45°F
The warmest month (with the highest average high temperature) is August (76.3°F).
The month with the lowest average high temperature is December (43.7°F).
- Average low temperature in January: 36°F
The month with the highest average low temperature is August (54°F).
The coldest month (with the lowest average low temperature) is December (35.1°F).
Average pressure in January
SeattleWA
- Average pressure in January: 30.1"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The months with the lowest atmospheric pressure are MarchAugust and September (30.01"Hg).
Average wind speed in January
SeattleWA
- Average wind speed in January: 5.2mph
The windiest month (with the highest average wind speed) is March (5.3mph).
The calmest months (with the lowest average wind speed) are July and August (3.5mph).
Average humidity in January
SeattleWA
- Average humidity in January: 85%
The month with the highest relative humidity is January (85%).
The month with the lowest relative humidity is July (69%).
Average rainfall in January
SeattleWA
- Average rainfall in January: 0.71"
The wettest month (with the highest rainfall) is December (0.87").
The driest months (with the least rainfall) are July and August (0.12").
Average rainfall days in January
SeattleWA
- Average rainfall days in January: 8.8 days
The month with the highest number of rainy days is November (9.1 days).
The month with the least rainy days is August (2.8 days).
Average snowfall in January
SeattleWA
- Average snowfall in January: 0.12"
The month with the highest snowfall is February (0.71").
The months with the least snowfall are AprilMayJuneJulyAugustSeptemberOctober and December (0").
Average snowfall days in January
SeattleWA
- Average snowfall days in January: 1.3 days
The month with the highest number of snowfall days is February (1.9 days).
The months with the least snowfall days are MayJuneJulyAugustSeptember and October (0 days).
Average sea temperature in January
SeattleWA
- Average sea temperature in January: 45.6°F
The best month for swimming (with the highest average sea temperature) is August (53.5°F).
The coldest month (with the lowest average sea temperature) is February (45.3°F).
Average daylight in January /
Average sunshine in January
SeattleWA
- Average daylight in January: 9h and 0min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in January: 4h and 2min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is December (Average sunshine: 4h and 18min).
Average sunshine days in January
SeattleWA
- Average sunshine days in January: 18.8 days
The month with the most sunshine days is August (25.9 days).
The month with the least sunshine days is November (16.8 days).
Average UV index in January
SeattleWA
- Average UV index in January: 2
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are JanuaryFebruaryNovember and December (UV index 2).
Average cloud cover in January
SeattleWA
- Average cloud cover in January: 55
The month with the most cloud cover is December (Cloud cover 56).
The month with the least cloud cover is August (Cloud cover 25).
Average visibility in January
SeattleWA
- Average visibility in January: 5mi
The months with the highest visibility are AprilMayJuneJulyAugustSeptember and October (6mi).
The months with the lowest visibility are JanuaryFebruaryMarchNovember and December (5mi).
