There have been more than 600 confirmed flu cases registered by NSW Health overnight, according to the State Opposition, bringing the July total to 4085.
Shadow Health Minister Walt Secord says the Berejiklian Government has failed to adequately prepare for the season.
"On the Central Coast there have been 289 cases so far this year," Mr Secord said.
"To give some context, in the month of January (there were) 13 cases, in June 100 cases, and as of this morning 117 cases for July.
"Flu cases affect the Emrgency Departments, it means patients (with other illnesses) wait longer than they should."
So far, this year, NSW has experienced 11,176 flu cases, nearly 2500 more than last year according to the Health database.