Below is a list of Winthrop IA zip codes. For your research we have also included Winthrop Area Code, Time Zone, UTC and the local Buchanan County FIPS Code. Each Winthrop Iowa zip code has a center Longitude / Latitude point (the Winthrop center is -91.731796264648 / 42.473899841309). For your convenience we have also indicated if that zip code in Winthrop observes Daylight Savings time.