They will probably love it and thank you for moving to vacation land. Horses in many walks of life travel all over the planet with little or no difficulty. I would start adding some flavoring to their water so that hydration does not become an issue, and bring plenty of the hay to which they are accustomed so you can mix it with their new hay. It should not be as drastic as if you were to move them during the summer months. At this season, they will have time to adjust to the heat and humidity. At least, that is how I see it.
It is never the horse's fault