I tiles in stone effect porcelain stoneware are always frost-resistant products, regardless of who produces them. There is therefore no issue with laying them outside. 

The advice is to check the state of the plaster, which must not have any cracks or raised areas (all problems that must be resolved prior by removing them together with any paint). We recommend the use of high-quality cement-based adhesives, suitable for outdoors and with good flexibity and used in conjunction with the Mapesil elastic joint products from Mapei.