Olney, Missouri experiences a humid continental climate, characterized by hot summers and cold winters. Average temperatures range from the low 20s in winter to the high 80s in summer. Precipitation is spread throughout the year, with slightly more rainfall during the summer months.

Hydrologically, Olney lies in the Upper Mississippi River Basin. The area is home to several creeks and small rivers that eventually flow into the Mississippi River. These waterways provide opportunities for fishing, canoeing, and kayaking.

Outdoor enthusiasts in Olney can enjoy various recreational activities. The nearby Mark Twain National Forest offers hiking, camping, and bird watching. Raccoon Creek Conservation Area provides opportunities for hunting, fishing, and wildlife viewing. Additionally, there are several parks and trails in and around Olney, making it a great destination for nature lovers and outdoor adventurers.