Cantaloupes are typically at their peak in the months of June through September. They start to be sold at the beginning of summer through spring. Although this is the case, cantaloupes are in fact sold at different times of the year in places throughout the world, though in the U.S this period of time is usually in the summer and spring seasons.
This is typically when they can be found in most grocery stores throughout the country, though you will definitely find that they are more prevalent in certain areas more so than others. Those who are thinking about growing their own cantaloupes will want to make a point of choosing the beginning of the summer around June to do it because this is when they are able to grow their best.