Marne, Iowa is a small town located in Cass County, in the central part of the state. The area experiences a humid continental climate, characterized by hot summers and cold winters. Average temperatures range from around 20°F (-6°C) in winter to 85°F (29°C) in summer. Marne receives about 30 inches of precipitation annually, evenly distributed throughout the year.

Hydrologically, Marne is situated in the West Nishnabotna River watershed, with numerous streams and creeks flowing through the region. The West Nishnabotna River itself provides fishing opportunities for anglers, with species like catfish, bass, and bluegill commonly found. Additionally, the area has several small ponds and lakes that offer recreational boating and water sports activities.

Outdoor enthusiasts in Marne can explore the surrounding countryside, which offers diverse opportunities for hiking, biking, and camping. The nearby Yellow River State Forest provides over 25 miles of trails for hiking and horseback riding. The area is also known for its scenic beauty, making it an ideal destination for nature photography and birdwatching. Overall, Marne offers a pleasant climate, varied water resources, and abundant outdoor recreation opportunities for residents and visitors alike.