California Governor Gavin Newsom on Sunday said there could be a potential third wave of the coronavirus and policymakers need to be “humbled” by what they do not know about SARS-CoV-2.

Policymakers have been expressing concerns about a potential second wave this fall, but the California governor on CNN went further, saying previous pandemics like the one in 1918 had multiple waves.

“If history doesn’t repeat itself, it certainly rhymes. And the realities of previous pandemics around the globe and those we experienced in the United States suggest not just second waves, but potential third waves,” Newsom said. “And so one has to be very, very sober as we move forward to this next round of re-openings, and do so with the modifications that are required of the moment, and,  I think, a humbleness of spirit on all sides of the political aisle that’s also needed at this moment.

Newsom was responding to questions about how quickly schools will re-open and if there will be major gatherings like sporting events and concerts this year in the Golden State.

He predicted that “some school will not be” ready to open in the fall though “many schools will be.”

“And it’s all conditioned on our ability to not only keep our children safe, but to keep staff and faculty safe, to keep the community safe. So, it’s all predicated on data, on science, on not just observed evidence, the reality on the ground,” Newsom said. “So, I think it’s a question that is a difficult one to answer in absolute terms. There’s nuance. But we are moving forward, in hope and expectation that we can start that school year very strategically and methodically, again, based upon the health as a prime frame of reference in terms of those decisions.”

Newsom added that “each part of California is unique and distinctive” and “certain conditions will present themselves favorably, some unfavorably.”

“But, look, I’m a father of four kids, and deeply anxious about their health and safety, as every parent watching is as well. And so it’s just another proof point. Those that claim we know what we know about this pandemic, it was 90 days ago no one even knew the word Covid, let alone what corona actually meant,” he continued. ” And so we are in a situation where, every day, we have to be humbled by what we don’t know, and we have to be open to argument, interested in evidence. You cannot be ideological about this disease, and nor — forgive me for belaboring — can we be naive.”

Newsom, pointing out that businesses are re-opening with plenty of “modifications,” also gave realistic expectations about major sporting events returning this fall with crowds, saying that the health consequences associated with packed stadiums could be “profound.”

“So, when you look for the future, you have got to paint a picture of those modifications, where people are practicing physical distancing, or should be, where people are putting face coverings on when they otherwise are coming into contact with strangers,” Newsom said. “But the idea of having stadiums filled with 80-plus-thousand people, strangers coming together across their differences, as much as we want to see that happen, and the spirit and the pride that comes from people coming together in that respect, the health consequences could be profound and devastating and set back all the progress we have made.”

The California governor said state officials “are moving into that very cautiously, working with all the major leagues across the spectrum, to make sure that” they are “not promoting things or promising things” that they “can’t deliver.”