Dr David Rosser, chief executive of University Hospitals Birmingham NHS Foundation Trust, said hospitals were in control of dealing with the Covid-19 and "nowhere near" reaching a point where no additional patients could be received.
But he said he had serious concerns that people who head out into the sunshine over the weekend could spread the illness, leading to pressure piling on to the region's hospitals in the coming weeks.
It came as West Midlands Police chief constable Dave Thompson warned that officers would be on patrol in large numbers in the coming days on the lookout for people who break the rules.
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Dr Rosser said: "We remain pretty concerned about this nice weekend we are coming into. There is something in the psyche about a bank holiday weekend that people want to go out, but the fact that people are staying at home anyway shouldn't really make any difference.
"The problem with this virus is that if people do break the rules and go out this weekend, it will be five to 10 days before we start seeing the impact on hospitals.
"That is what we are most nervous about, that people are falsely reassured that this is over and towards the end of the week we start reaping the consequences.
"It's not that I think we are going to get busy this weekend. But if people take home the wrong message it could cause us trouble for next weekend."
As of Friday, 365 coronavirus patients had died in the care of the University Hospitals Birmingham trust which runs Queen Elizabeth Hospital as well as Good Hope, Heartlands and Solihull hospitals.
That is 113 more deaths than any other health trust in the country.
Dr Rosser spoke as the new Nightingale Hospital at the NEC started trials ahead of fully opening in the coming days.
Mr Thompson praised people in the West Midlands for making the force's job "a lot easier" by committing to the 'stay at home, save lives' approach.
He said that since lockdown started on March 23 the force had issued 155 instructions for people who had ignored the advice to go home, resulting in 138 notices of dispersal and 17 fixed penalty notices.
And he said the lockdown had seen demand on the police had fall by a quarter, with robbery dropping by almost 60 per cent.
"A lot of the work we traditionally do is not here, so we are out and about encouraging the public to follow these guidelines strongly," he said.
"There are thousands of interactions happening every day, and the public are responding to what the police are saying.
"'Stay at home' does save lives, and it protects our NHS. I trust the public hears that message and will be working very hard to keep it."