Iowa Code § 1D.1: Standard time and daylight saving time.

The standard time in this state is the solar time of the ninetieth meridian of longitude west of Greenwich, England, commonly known as central standard time, except that from 2:00 ante meridiem of the first Sunday of April in every year until 2:00 ante meridiem of the last Sunday of October in the same year, standard time shall be advanced one hour. The period of time so advanced shall be known as “daylight saving time”.