The National Weather Service issued a weather alert at 1:16 p.m. EDT on Sunday for patchy frost until Monday at 7 a.m. EDT for Cass, St. Joseph, Branch, Hillsdale and Berrien counties.“Temperatures have a chance to drop below 40 degrees tonight across extreme southern Lower Michigan. Should clouds be more isolated as opposed to broken or scattered, it is possible that outlying areas receive patchy frost tonight. If you live in an area where it t…