The high temperature of 34 in Grand Rapids was the coldest high temperature on any April 17 iin history (records go back to the 1800s). For Muskegon it was not only the coldest high temperature for the day, it was also the coldest high temperature this late in the season.
This map shows temperature difference from average for April 1-17. It was warmer than average in the Florida Peninsula and from California east to West Texas. The coldest air relative to average was in the Northern Plains and Great Lakes. Actually, if you include central Canada, it was the coldest area relative to average int he world. For April 1-17, the contiguous U.S. was 4.66 deg. colder than average.