Below is a list of Dubuque County IA zip codes. For your research we have also included Dubuque County Area Code, Time Zone, UTC and the local County FIPS Code. Each Dubuque County Iowa zip code has a center Longitude / Latitude point (the Dubuque County center is -90.874900817871 / 42.478500366211). For your convenience we have also indicated if that zip code in Dubuque County observes Daylight Savings time.