Arnold, located in Jefferson County, Missouri, has a humid subtropical climate with hot summers and mild winters. The average temperature varies from 23°F to 90°F. The city is situated in the Mississippi River watershed and is home to several small streams. The water quality of these streams is affected by sedimentation, nutrients, and bacteria. The city also has several parks and outdoor recreation opportunities, including the Meramec Greenway Trail, which is a 10-mile paved trail great for walking, running, and biking. The Arnold City Park has a playground, pavilion, and walking trail, while the Pomme Creek Golf Course offers a great golfing experience. The city also has several local restaurants and shops to enjoy.