Officials in San Bernardino County, California, issued an evacuation after a brush fire spread to over 3,000 acres.

Some Southern California residents were forced from their homes Saturday after an explosive wildfire grew by more than 3,000 acres in mere hours – and is burning so intensely that it is creating its own weather.

The battle against a wildfire also got a boost in South Dakota thanks to cooler weather and lighter winds. Residents of the state's second-largest city have been on edge, ready to flee if flames from a nearby blaze moved dangerously close.

A blaze near the remote Northern California mountain community of Sierra Brooks was uncontained. Authorities expanded evacuation orders for a total of more than 530 residents Tuesday evening after strong winds pushed flames through dry brush and timber about 50 miles north of Lake Tahoe.

Californians are being warned to prepare to swelter as a scorching heatwave settles over the state this week, marking the high point of an already hot summer.