Multiple small fires were reported in the Angeles National Forest on Saturday morning due to lightning strikes.

Extreme heat across the U.S. Southwest will build on Wednesday and is expected to last for several days. In Southern California, there are major fire and health concerns.

The peak of the heat wave is expected Thursday and Friday, the National Weather Service said. While it’s brought hotter temperatures than in recent weeks, it is not particularly extreme in terms of all-time Southern California highs. “This is definitely more normal heat for this time of year,” Sam Zuber, an NWS meteorologist said.