Jerry,
I commute daily in all weather in Seattle. We don't have much snow or any salt but it rains A LOT. I use a Dahon Helios XL which is very well suited to adverse weather. It has full fenders, an Aluminum frame, an 8 speed internal gear hub and a stainless steel chain. I have had it for 9 months and have logged just over 1900 miles on it. The brakes seem to need more frequent adjustment than I'm used to and the insides of the folding mechanisms need to be kept very clean, but no more messing with derailers is a welcomed switch. I rode many folders and reviewed even more and found this model to be the best combination of price, quick fold, durability, and low maintenance. I recommend it as good commuting equipment.