Gov. Charlie Baker at a State House press conference. (Pool photo by Nicolaus Czarnecki)

THE NUMBER of new COVID-19 cases in Massachusetts rose by 438 on Tuesday, the highest one-day increase since June 6.

The increases of late have been erratic even as the public’s focus on them has increased amid concerns the coronavirus is returning in strength and Gov. Charlie Baker has appealed to residents to exercise caution.

The number of new cases on Monday was 165 and on Sunday it was 353. The positive test rate (new cases divided by the total number of tests) rose to nearly 2.9 percent on Tuesday, pushing up the seven-day average to nearly 2.3 percent.

Baker has been saying for several days now that he will take action if the number of cases continues to rise, but he has declined to say what would trigger a response.

“We’ve only had a slight uptick from a low of 1.7 percent to 2 percent, but we’ll be forced to adjust our plans if the data warrants it,” Baker told reporters following a tour of the MedFlight headquarters in Bedford. “That could mean gathering sizes could be reduced or we could make some of our business regulations more strict. Reopening and staying open is obviously a big part of the goal, but, obviously, we can’t do that if we don’t have everybody’s help to continue to move forward.”

Bruce Mohl oversees the production of content and edits reports, along with carrying out his own reporting with a particular focus on transportation, energy, and climate issues. He previously worked...