Yes. Hazorea Biosecure Koi have been sold successfully for many years in Canada, Scandinavia, and other countries where ponds freeze over in winter. Koi Carp can withstand cold temperatures wherever they were born and raised, provided they are given time to acclimate. Hazorea Biosecure Koi are no different and need a period of a few weeks to adjust to cold (under 10ºC/50ºF) temperatures. So if you bought your Koi in summer they should have no problem adjusting to the changing seasons.