Harvest when the fruits are full-sized and the skins are tough. The bottoms (sides that touch the ground) of mature fruits are usually cream to orange-colored. Cut squash from the vines with an inch or two of the stem attached. Light frost will not hurt mature fruits but it’s best to harvest them as soon as they are ripe. Store at 50°F in a dry place.
Here is a link to more information: Harvest and Store Your Winter Squash