May weather in Mercer Island, WA
The average temperature in Mercer Island in May is 57.9°F (49.3°F–66.5°F). Average precipitation: 1.98 inches.
May is a spring month in Mercer Island, and is warmer than the annual average of 53.8°F. Daily temperatures swing about 17.2°F between overnight low and afternoon high. Expect about 11 days with precipitation. Daylight averages about 14h 55m. For travel, May is a comfortable month to visit.
Avg High
66.5°F
Avg Low
49.3°F
Precipitation
1.98 in
Daylight
14h 55m
May records in Mercer Island
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| May 1 | 88.0°F (2014) | 30.0°F (1954) | 0.79 in (1949) |
| May 2 | 87.1°F (2016) | 33.1°F (1952) | 0.45 in (2007) |
| May 3 | 77.0°F (1953) | 37.0°F (1963) | 1.19 in (2014) |
| May 4 | 86.0°F (1953) | 37.0°F (1952) | 0.59 in (2010) |
| May 5 | 90.0°F (1953) | 37.0°F (1949) | 0.96 in (2009) |
| May 6 | 86.0°F (2013) | 37.0°F (2002) | 0.63 in (2009) |
| May 7 | 82.0°F (2016) | 35.1°F (2002) | 0.35 in (1953) |
| May 8 | 78.1°F (1949) | 37.9°F (1999) | 0.41 in (2014) |
| May 9 | 87.1°F (2020) | 39.0°F (1999) | 0.68 in (2000) |
| May 10 | 87.1°F (2020) | 37.0°F (1999) | 0.32 in (2004) |
| May 11 | 84.9°F (2024) | 39.0°F (1953) | 0.52 in (2011) |
| May 12 | 84.9°F (1959) | 39.0°F (2011) | 0.41 in (1948) |
| May 13 | 82.0°F (1959) | 37.9°F (1956) | 0.50 in (2009) |
| May 14 | 86.0°F (2023) | 32.0°F (1999) | 0.81 in (2011) |
| May 15 | 91.0°F (2023) | 32.0°F (1999) | 0.63 in (2001) |
| May 16 | 82.0°F (2006) | 32.0°F (1999) | 0.39 in (2020) |
| May 17 | 89.1°F (2008) | 32.0°F (1999) | 0.56 in (2025) |
| May 18 | 87.1°F (1958) | 39.0°F (2003) | 0.75 in (2005) |
| May 19 | 88.0°F (1963) | 41.0°F (2003) | 0.42 in (2009) |
| May 20 | 89.1°F (1963) | 41.0°F (1955) | 0.56 in (2007) |
| May 21 | 93.0°F (1963) | 42.1°F (1960) | 0.92 in (1957) |
| May 22 | 84.9°F (1951) | 39.0°F (1960) | 0.23 in (2006) |
| May 23 | 84.0°F (2001) | 39.9°F (1950) | 0.57 in (1962) |
| May 24 | 80.1°F (1948) | 43.0°F (1950) | 0.42 in (1953) |
| May 25 | 82.9°F (1950) | 36.0°F (1964) | 0.28 in (2014) |
| May 26 | 89.1°F (2005) | 43.0°F (1952) | 0.57 in (2004) |
| May 27 | 88.0°F (2005) | 43.0°F (1954) | 0.66 in (1948) |
| May 28 | 82.9°F (2015) | 42.1°F (1951) | 0.61 in (1948) |
| May 29 | 82.0°F (2009) | 39.0°F (1951) | 0.35 in (1948) |
| May 30 | 87.1°F (1956) | 39.9°F (1951) | 0.72 in (2020) |
| May 31 | 89.1°F (1964) | 41.0°F (1953) | 1.11 in (2005) |