The reports say the number of cases in the Lanaudiere region is up to 80, a significant jump from 32 at the end of February.
The health department in the region is refusing to answer queries about the number.
A staff member said the situation was evolving but would not confirm any figures until a news conference scheduled for Wednesday morning in Joliette.
The CBC says all of the cases involve unvaccinated children and adults and are traced to an outbreak at a California amusement park.
All the Quebec cases have been centred in the Lanaudiere region and are part of one chain of transmission that started when a person who became infected at Disneyland returned to the province.
In late February, Quebec health authorities said several dozen other people were under observation because measles have a two-week incubation period.
There have also been 18 cases of measles confirmed in Ontario and a single case in Manitoba.