Evacuation orders were issued across Mendocino, Lake and nearby Colusa counties, though some people were allowed to return home on Monday afternoon, Cal Fire said - more than 20,000 people have been evacuated.
The Mendocino Complex Fire has already engulfed 290,692 acres (117,639 hectares) - nearly the size of Los Angeles.
It is one of two major wildfires in California, the other one being the Carr fire, about 260km north of state capital Sacramento.
"Fire season is really just beginning", Cal Fire Director Ken Pimlott said, explaining that such intense conditions used to come around the peak of the season.
The Mendocino Complex fire has not killed anyone so far.
A brand new blaze called the Holy Fire was ignited on Monday in Orange County, quickly expanding to more than 1,200 acres.
Seven people have died in the blaze, including two firefighters.
More than 14,000 personnel from California and elsewhere in the country are fighting wildfires across the state.
Trump's tweet comes after California water officials ignited a debate this summer by proposing a plan to limit the amount of water that can be drawn from the San Joaquin River for use in cities and farmlands.
Firefighters fight to save a structure on New Long Valley Rd as the Ranch Fire burns near Clearlake Oaks, California, on Saturday, August 4, 2018.
"We are routinely now seeing fires reach 100,000 acres several times in one month and it's only July, so we have a long way to go in this fire season, and as we saw a year ago fire season can go right up through December".
Another major fire also burning in Northern California, the Ferguson Fire, extended into its third week. "The fire's not going to get up and move", Hoon said.
Fire officials have condemned the presidents comments, saying that they are not in fact struggling to source enough water to contain the fires. WITCH FIRE (San Diego County), October 2007 Acres burned: 197,990 Structures destroyed: 1,650 Deaths: 2 9. Firefighting aircraft can dip in and out of cattle ponds or other small bodies of water to scoop up water for dropping and spraying on flames.
The Pentagon will send about 200 soldiers from the state of Washington to help civilian firefighters battle at least one blaze as wildfires burning in 11 western states soak up resources.
The Ranch Fire is the larger of the two fires, having consumed more than 225,000 acres so far.