January weather in Mercer Island, WA
The average temperature in Mercer Island in January is 42.7°F (36.8°F–48.6°F). Average precipitation: 5.21 inches.
January is a winter month in Mercer Island, and is cooler than the annual average of 53.8°F. Daily temperatures swing about 11.8°F between overnight low and afternoon high. Expect about 19 days with precipitation. Daylight averages about 8h 38m. For travel, January is a wet month.
Avg High
48.6°F
Avg Low
36.8°F
Precipitation
5.21 in
Daylight
8h 38m
January records in Mercer Island
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| January 1 | 55.9°F (2006) | 14.0°F (1952) | 1.55 in (1964) |
| January 2 | 59.0°F (2003) | 12.0°F (1950) | 1.46 in (2021) |
| January 3 | 61.0°F (2020) | 10.9°F (1950) | 0.86 in (1956) |
| January 4 | 55.9°F (2003) | 15.1°F (1959) | 1.01 in (1956) |
| January 5 | 57.9°F (2015) | 19.0°F (2004) | 1.23 in (2006) |
| January 6 | 59.0°F (2002) | 18.1°F (2017) | 1.17 in (1956) |
| January 7 | 63.0°F (2002) | 25.2°F (2017) | 1.45 in (2009) |
| January 8 | 57.0°F (1953) | 21.0°F (1949) | 1.33 in (1959) |
| January 9 | 55.9°F (1953) | 15.1°F (1949) | 1.36 in (2006) |
| January 10 | 59.0°F (1961) | 15.1°F (1949) | 1.02 in (2006) |
| January 11 | 59.0°F (2014) | 17.1°F (1949) | 1.14 in (1953) |
| January 12 | 57.9°F (1956) | 15.1°F (1963) | 1.49 in (2021) |
| January 13 | 59.0°F (2026) | 12.9°F (1950) | 0.66 in (2011) |
| January 14 | 60.1°F (2023) | 10.0°F (1950) | 0.98 in (1958) |
| January 15 | 62.1°F (2018) | 16.0°F (1950) | 0.94 in (1956) |
| January 16 | 57.0°F (2011) | 16.0°F (1950) | 1.58 in (1958) |
| January 17 | 57.0°F (2018) | 18.0°F (1950) | 1.97 in (2005) |
| January 18 | 61.0°F (2005) | 12.0°F (1950) | 1.21 in (2017) |
| January 19 | 63.0°F (2005) | 21.0°F (1962) | 1.67 in (1950) |
| January 20 | 57.9°F (2010) | 19.0°F (1954) | 1.24 in (1950) |
| January 21 | 61.0°F (2005) | 12.9°F (1962) | 2.15 in (1954) |
| January 22 | 57.0°F (2016) | 17.1°F (1962) | 0.99 in (1953) |
| January 23 | 57.9°F (2005) | 19.9°F (1949) | 1.25 in (1959) |
| January 24 | 62.1°F (2015) | 14.0°F (1949) | 0.99 in (2002) |
| January 25 | 64.9°F (2015) | 10.0°F (1950) | 0.76 in (2002) |
| January 26 | 64.9°F (2015) | 8.1°F (1957) | 0.75 in (1959) |
| January 27 | 60.1°F (1952) | 9.0°F (1957) | 0.81 in (1999) |
| January 28 | 61.0°F (2024) | 10.0°F (1950) | 0.95 in (1999) |
| January 29 | 60.1°F (2024) | 6.1°F (1950) | 1.67 in (2004) |
| January 30 | 59.0°F (1960) | 10.0°F (1950) | 0.96 in (1961) |
| January 31 | 64.0°F (1960) | 3.0°F (1950) | 0.69 in (1963) |