Aetna Township experiences a humid continental climate (Köppen climate classification *Dfb*), featuring four distinct seasons.
* **Summers:** Warm and humid, with average July highs around 82°F (28°C). * **Winters:** Cold and snowy, with average January lows dipping to 13°F (-10°C). * **Precipitation:** The township receives approximately 35 inches of rain annually. * **Snowfall:** Due to its location in western Michigan, the area is subject to lake-effect snow from Lake Michigan, averaging 60 to 70 inches of snow per year. * **Best Time to Visit:** Late spring through early autumn (May to October) offers the most comfortable weather for outdoor recreation.