You can safely leave your board out for about 2 hours at room temperature. If it is really hot, or if you want to leave your board out for more than 2 hours try this trick: - Place a layer of kitchen towels on your board, top with thin ice packs like these. - Add another layer of towels, then top with wax paper (the towels help absorb moisture from the ice packs) - Place the cold items over the ice packs. - For the hot items, use a chafing dish or heat a stoneware dish in the oven and keep the hot food on top of it.