Multiple Mailing Addresses Based on Time of Year
You could also add the two adresses as to different adress types. One is set as primary, and then you need some help on changing what adress is primary, based on time. I do think CiviRules could help you with that, giving a specific time of the year, where you change what adress is set as primary. If you want to go that route, let me know and I could help you with giving tip on specific trigger and condition to use.