Below is a list of Mercer Island WA zip codes. For your research we have also included Mercer Island Area Code, Time Zone, UTC and the local King County FIPS Code. Each Mercer Island Washington zip code has a center Longitude / Latitude point (the Mercer Island center is -122.22699737549 / 47.574600219727). For your convenience we have also indicated if that zip code in Mercer Island observes Daylight Savings time.