Wildfires spreading in parts of California could get worse from Monday, aggravated by strong winds that are likely to fan flames caused by lightning strikes, CNN reported.

The thousands of lightening strikes over the past several days have ignited hundreds of small wildfires in the northern part of the state.

More than 9,300 firefighters are fighting the 21 wildfires, according to the California Department of Forestry and Fire Protection.

NBC News reported that a firefighter died on Saturday while fighting the so-called Frog Fire, about 100 miles south of Oregon.

Rocky Fire, the most massive of the wildfires, has already destroyed 54,000 acres in three counties and is only 5 percent contained as of now.  It is burning in Lake, Yolo and Colusa counties northwest of Sacramento.

"This has been a very fast-moving wildfire with the dry conditions, and the weather not really cooperating with us over the past week," CalFire Spokesperson Daniel Berlant said.

More than 12,100 people in the region had been advised to evacuate their structures as of Sunday afternoon.

More than 134,000 acres have been burnt down in California by the ongoing fires, according to Cal Fire.

The firefighters are able to make more headway during the night because of the rise in humidity and the decrease in the fire activity.