I am looking at Cape Cod rentals for next September. Which is preferable? Bay side or ocean side?
Thanks.

Bay side has gentle surf and significant high and low tides.Ocean side has much colder water and crashing surf.Which town are you planning on?

One town, bay side, is in Dennis, and the other Dennis Port on the ocean side.

Dennis and Dennisport are both in the town of Dennis. With a Dennis beach sticker you can use the beaches on both the bay and Nantucket Sound.

I just noticed you will be there in September, so you probably won’t need a beach sticker for any of the town beaches.

Dennisport is on Nantucket Sound, not the ocean. There is no surf on the sound, and the water is warm. The bay beaches are cooler, but not as cold as the ocean. I prefer the bay side for swimming. At low tide, you can walk a long way out on the sand of the bay, as it is very tidal, much more so than the sound. If either rental is walkable to the beach, that is nice. You can drive to all the other beaches.

You will probably want to drive to the ocean beaches at some point, which are the east-facing beaches. There are ocean beaches at the Cape Cod National Seashore and at town beaches in Chatham, Orleans, Eastham, Wellfleet, and Truro. The water is cold and there is strong surf.

The water in the bay is SO much warmer!

The water in the bay is much warmer than the ocean. But Dennisport is not on the ocean, it is on Nantucket Sound, which is warmer than the bay.

The National Seashore,which begins on the ocean side in Eastham is a National Park and a treasure.Beaches above Orleans tend to be less crowded and there is a bit more rural feeling,as well.

September is a fine time to visit the Cape as the crowds go way down once the kids are back in school and it is still warm enough to swim.

I prefer the area from Eastham to Provincetown, and like both sides which are so close you can visit both in a day. I'm not sure when the parking sticker requirements are lifted, but perhaps someone else knows. I know when we go off season we can park at all the beaches.

The Atlantic Ocean begins at the Cape's elbow, Chatham, Orleans and so on until the land curves to the Bay at Provincetown. The ocean is cold in spring, warms up by Aug, Sept. Nantucket Sound is on the south side of the Cape and Mass, small waves, warmer. Bay on the north side, calmer. The Sound side has many nice beaches. When our kids were small we went to the Sound, Bay or one of the many fresh water lakes so they could comfortably and safely go in the water.Swimming lessons were at one of the lakes. It all depends on what you are looking for.