The mountain's name is taken from the river's name, which was applied by Albert Hale Sylvester (1871-1944), a pioneer surveyor, explorer, topographer, and forest supervisor in the Cascades.

[5] Chiwawa Mountain is located in the Cloudy Pass batholith, an intrusive formation that was formed approximately 20 million years ago, during the early Miocene.

[3][6] During the Pleistocene period dating back over two million years ago, glaciation advancing and retreating repeatedly scoured and shaped the landscape.

[3] Uplift and faulting in combination with glaciation have been the dominant processes which have created the tall peaks and deep valleys of the North Cascades area.

[3] Due to its temperate climate and proximity to the Pacific Ocean, areas west of the Cascade Crest very rarely experience temperatures below 0 °F (−18 °C) or above 80 °F (27 °C).