Is it ok to run dryer on a non heated porch in winter?

In my experiences of having a dryer in an enclosed back porch (in the country) I had no trouble getting the clothes to dry. If you have a gas dryer it MUST be vented to the outside (if porch is enclosed).

If the porch you are running the dryer from is open, the only thing I would suggest is putting some sort of mesh over the end of the exhaust vent to catch the lint from getting all over the neighborhood/yard.

Hope this helps.