The governor made the announcement on MSNBC's "Morning Joe."
"There’s no question that face coverings are game-changers," Murphy said. "I think we were the first state in America to require them indoors.
"They’ve been strongly recommended out-of-doors. We’re gonna turn that up a notch today and say, We’re gonna ask you: If you can’t socially distance, it’s gonna be required."
The move comes days after the transmission rate climbed over 1 for the first time in 10 weeks. That means every new case of COVID-19 is transmitted to at least one more person.
Face masks have been mandatory at stores, while riding public transportation and while indoors since April.
The new rule says those who can't stay six feet away from others while in large groups in outdoor settings will be required to wear a mask.
A penalty for violators was not mentioned by Murphy.
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