I don't know what are the climatic conditions are involved in this
case but in the UK and other European countries ferrets are often kept
outside all year round.

In the UK the temperature can vary from -10C (14F) to over 32C (90F),
these are extremes and vary rarely reached. Provide the ferrets
accomodation can provide dry shelter, plenty of shade and fresh air
in summer and warmth with added insulation in winter then the ferrets
suffer no ill effects. They have thick plush coats in winter and
certainly are not upset by warm weather given plenty of ventilation.

See Scandinavian ferrets at..
http://naturalferrets.com/forum/viewtopic.php?f=8&t=16529

Tony.
My home is ferret proof - my heart is not.

[Posted in FML 6243]