Record temperatures range from 18 °F (-8 °C) on January 15, 1911, up to 118 °F (48 °C) on July 17, 1925, June 16, 1917, and July 6, 2018.

Lake Mathews is surrounded by approximately 4,000 acres of protected land. In the early 1990s, an additional 9,000 acres was added to the reserve after the discovery of the endangered Stephen's kangaroo rat (Dipodomys stephensi) in the area. The area is now called the Lake Mathews Estelle Mountain Reserve.