Mercer Island Weather in January
Average highs run from 48°F on January 1 to 50°F on January 31, and lows from 36°F to 37°F. Normal precipitation for the month is 5.21 in over about 19 wet days.
January day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
January at a glance
- Average high
- 49°F
- Average low
- 37°F
- Precipitation
- 5.21 in
- Snowfall
- 0.9 in
- Record high
- 65°FJan 25, 2015
- Record low
- 3°FJan 31, 1950
- Chance of a freeze
- 97%
- Daylight
- 8 h 31 min to 9 h 33 min
- Cloud cover
- 72%
- Humidity
- 92%
- Dew point
- 32°F
- Wind
- 5.6 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| Jan 1 | 48°F | 36°F | 56°F 2006 | 14°F 1952 | 61% | 3% |
| Jan 2 | 48°F | 36°F | 59°F 2003 | 12°F 1950 | 62% | 3% |
| Jan 3 | 48°F | 36°F | 61°F 2020 | 11°F 1950 | 62% | 3% |
| Jan 4 | 48°F | 36°F | 56°F 2003 | 15°F 1959 | 62% | 3% |
| Jan 5 | 48°F | 36°F | 58°F 2015 | 19°F 2004 | 62% | 3% |
| Jan 6 | 48°F | 37°F | 59°F 2002 | 18°F 2017 | 62% | 3% |
| Jan 7 | 48°F | 37°F | 63°F 2002 | 25°F 2017 | 61% | 3% |
| Jan 8 | 48°F | 37°F | 57°F 1953 | 21°F 1949 | 61% | 3% |
| Jan 9 | 48°F | 37°F | 56°F 1953 | 15°F 1949 | 61% | 3% |
| Jan 10 | 48°F | 37°F | 59°F 1961 | 15°F 1949 | 61% | 3% |
| Jan 11 | 48°F | 37°F | 59°F 2014 | 17°F 1949 | 61% | 3% |
| Jan 12 | 48°F | 37°F | 58°F 1956 | 15°F 1963 | 61% | 3% |
| Jan 13 | 49°F | 37°F | 59°F 2026 | 13°F 1950 | 60% | 3% |
| Jan 14 | 49°F | 37°F | 60°F 2023 | 10°F 1950 | 60% | 3% |
| Jan 15 | 49°F | 37°F | 62°F 2018 | 16°F 1950 | 60% | 3% |
| Jan 16 | 49°F | 37°F | 57°F 2011 | 16°F 1950 | 60% | 3% |
| Jan 17 | 49°F | 37°F | 57°F 2018 | 18°F 1950 | 60% | 3% |
| Jan 18 | 49°F | 37°F | 61°F 2005 | 12°F 1950 | 60% | 3% |
| Jan 19 | 49°F | 37°F | 63°F 2005 | 21°F 1962 | 60% | 3% |
| Jan 20 | 49°F | 37°F | 58°F 2010 | 19°F 1954 | 59% | 3% |
| Jan 21 | 49°F | 37°F | 61°F 2005 | 13°F 1962 | 59% | 3% |
| Jan 22 | 49°F | 37°F | 57°F 2016 | 17°F 1962 | 59% | 3% |
| Jan 23 | 49°F | 37°F | 58°F 2005 | 20°F 1949 | 59% | 3% |
| Jan 24 | 49°F | 37°F | 62°F 2015 | 14°F 1949 | 59% | 3% |
| Jan 25 | 49°F | 37°F | 65°F 2015 | 10°F 1950 | 59% | 3% |
| Jan 26 | 49°F | 37°F | 65°F 2015 | 8°F 1957 | 59% | 3% |
| Jan 27 | 49°F | 37°F | 60°F 1952 | 9°F 1957 | 59% | 3% |
| Jan 28 | 49°F | 37°F | 61°F 2024 | 10°F 1950 | 58% | 3% |
| Jan 29 | 49°F | 37°F | 60°F 2024 | 6°F 1950 | 58% | 3% |
| Jan 30 | 49°F | 37°F | 59°F 1960 | 10°F 1950 | 58% | 3% |
| Jan 31 | 50°F | 37°F | 64°F 1960 | 3°F 1950 | 58% | 3% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (PST).
- January 1
- sunrise 7:57 AM, sunset 4:28 PM
- January 31
- sunrise 7:36 AM, sunset 5:09 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USW00024234 (Seattle Boeing Fld), public domain. Records: NOAA GHCN-Daily, station USW00024234, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.