"You see, we don't fully appreciate the genius of Donald Trump, who knows more than all the people of California, knows more than all the scientists," Sanders told the crowd of more than 5,000 people who braved 92 degree heat to hear the senator speak.
Sanders mentioned Trump's recent campaign stops in the Golden State ahead of the June 7 primary.
"[Trump] knows there is no drought. Not to mention, and I love this one, that Trump has concluded that climate change itself is a hoax," Sanders said.
Last week, the businessman made headlines when he argued the state was not actually suffering from drought.
"There is no drought. They turn the water out into the ocean," Trump declared during an event in the San Joaquin Valley less than an hour from where Sanders spoke Sunday.
The businessman blamed the state's water crisis on environmental policies, although the state has experienced record drought. Last year, California capped its driest four-year period on record and the state imposed emergency water restrictions after extremely low rainfall and snow in 2015.
"Together, despite Mr. Trump and his Republican colleagues, we are going to take on the fossil fuel industry. We are going to tell them that their short-term profits are not more important than the future of this planet," the senator added.
Sanders will continue his marathon rally schedule up the state, heading to Frenso and the Bay Area next.