"I am asking, when you are in public and around other persons, please put on your mask," Turner said. "We know that wearing a mask in public is one of the most effective methods to slow the spread of COVID-19."
The requirement to wear a mask was a statewide order put in place in July. Turner said the city has not been fining anyone, preferring instead to educate and distribute masks.
The order requires Texans must to wear a face covering "when inside a commercial entity or other building or space open to the public, or when in an outdoor public space, wherever it is not feasible to maintain six feet of social distancing."
Police officers will not respond to 911 calls reporting mask violations but will enforce the rule while on patrol and performing other duties in the public, Turner said.
Violators will be given a warning and will be asked to put on a mask, and if they refuse, they are subject to a $250 fine.
"It's time for people to do the right thing," Houston Police Department Chief Art Acevedo said. "We don’t want to write tickets."
Turner said July was hard on the city, with more cases and deaths than the previous four months.
Greater mask compliance is seen as a strategy for reducing the positivity rate and flattening the curve of daily new cases.
The city's positivity rate—the percentage of all tests with positive result—was 17.6% as of July 31; officials want that number at or below 5%.