The DQ near me (I am in Wisconsin) closed in winter. I am guessing they close because most people don’t eat a lot of ice cream when it is cold. This DQ was also right near Lake Michigan and a lot of their busienss was probably seasonal.
Ice cream is down on the sells list from the burgers and fries at all the DQs I’ve been to.
But, if you live in Milwaukee, there is always Leon’s custard. I believe they are open daily other than being closed Christmas and from noon til 3:00 on Good Friday.
Their Super Sunday is like a meal.