My wife and I rode through northern Ohio, but it was early/mid September and did not get much rain or cold weather. We have also ridden through North Dakota, Minnesota, and Michigan (twice) later in September and October. We had rain and below freezing weather at night and early mornings on both trips. I did not feel that I needed anything warmer than medium weight wool socks and my regular cycling shoes for the feet, and a pair of warm gloves.
We carry a light weight synthetic puff jacket, and several layer of tops. I carry a pair of light weight fleece pants that I use for skiing, which make a good layer for riding, and around camp in the evening. A fleece stocking cap is also nice.
Our camping gear during the shoulder season includes a good (a little heavier 3 season tent), 20 degree synthetic sleeping bags, and Thermarest pads.
We've done 28 tours, ranging from a week to 3 months, since 2003. I can only remember two tours that we did not get rained on; both were in California. On one tour we had 35 days of rain.
IMO a good rain jacket, rain pants and a helmet cover are a good combination for riding in cold, wet weather.
Michigan in October
Alberta, Canada-- The gear is pretty much what was outlined above.
A woman we camped next to on the Icefield Parkway in Alberta had a good fix for cold, wet weather.
