Another round of Santa Ana winds is forecast to sweep into Los Angeles on Thursday night into Friday morning, putting most of the region under a critical fire risk, as emergency responders battle to contain five quickly spreading wildfires.

The wind in the region relaxed overnight as the low pressure, which was helping enhance the wind, is moving away into Texas.

But high pressure is building from the north and that will help to tighten the pressure gradient over Southern California, producing more gusty winds.

Those winds may help spread the five sprawling wildfires that are spread around the Los Angeles area and that emergency responders are attempting to contain.

Thousands of structures have been damaged or destroyed and more than 100,000 people evacuated as uncontrolled infernos spread.

Red flag and high wind warnings have been issued through Friday afternoon for wind gusts 40 to 60 mph, with 70 mph possible in the mountains surrounding the California city.

Relative humidity could drop to as low as 5% for Southern California.

Because of the dry and windy conditions anticipated, a critical fire risk has been issued for much of the area for the next 24 hours.

An air quality alert has also been issued for Southern California, including Los Angeles, due to thick wildfire smoke and dust being blown around.

Smoke is forecast to engulf most of the Los Angeles basin.

ABC News’ David Brennan contributed to this report.