Officials warned young children and those with respiratory illnesses to take precautions. For weeks, smoke from Canadian wildfires has been drifting across the border.

New York City, Long Island and the Hudson Valley will all experience air quality within the 101-150 range on the air quality index Sunday, the state’s Department of Environmental Conservation forecasted—meaning the air could contain fine particles and could be “unhealthy for sensitive groups.”

A double whammy of wildfire smoke blowing into the city and an incoming heat wave has made the city's air dangerous for sensitive groups, according to the National Weather Service.