City of Sandusky issued the following announcement on Apr 5.
On Monday, April 4, 2022 Sanilac County will be conducting the annual test of the Emergency Warning System of the County.
The test will begin at 5:00 pm. At this time all warning sirens in the County will be activated by the local Fire Departments in the WARNING MODE.
At approximately 5:10 pm the ALL CLEAR will be activated.
A memo from the Sanilac County Emergency Management Director.... NOTE: This is a good time for the citizens of Sanilac County to test and practice their Emergency plans during the most realistic time of day for severe weather. I am asking all residents to review their plans within the next week and practice their plans during this testing of the County Warning System. And remind all residents that they should be prepared and have the needed materials and supplies to sustain themselves for 72 hours after the event.
Original source can be found here.