Gusty winds and humidity are helping fuel wildfires in the Northeast. No less than 27 million people, from New York to Massachusetts, are under fire alert as of Saturday afternoon.

Cities on fire alert include New York and Boston, where wind gusts of up to 35 mph and relative humidity of around 25 to 30 percent are expected.

Vegetation in the region also remains very dry, with this part of the country behind about 6 to 8 inches of precipitation since September 1. A cold front is expected to move through the area Sunday, bringing up to 1 inch of rain.

A Bush fire in Prospect Park in Brooklyn burned Friday night after about 2 acres of dry vegetation ignited during strong wind gusts, New York City firefighters said the. Firefighters worked through the night to put out the fire.

“This has been a historically dry period for New York City and more than 100 brush fires have occurred this month alone,” the FDNY said.

In Pennsylvania, firefighters are working to control a fire that broke out in Berks County due to dry and windy conditions. The fire broke out around 11:30 p.m. Friday on Neversink Mountain in Reading, where smoke could be seen rising from the fire.

The fire prompted the evacuation of nearby residents to Amanda E. Stout Elementary School, according to Reading Mayor Eddie Morán.

“The Pennsylvania Department of Conservation and Natural Resources (DCNR) Forestry Division will lead the firefighting and cleanup operation, which is expected to continue for several days, coordinating additional resources as needed,” Morán said .

In Passaic County, New Jersey, the 100-acre Cannonball 3 wildfire continues to burn with 0% containment, according to the New Jersey Wild Fire Department. Fifty-five structures are threatened by the fire, the cause of which is under investigation.

Another 39-acre wildfire in Bergen County is 40% contained, according to firefighters. A new fire, the Jennings Creed Wildfire, broke out Saturday afternoon in West Milford, Passaic County, and is also burning in Orange County, New York. It has already affected 1,800 acres and is threatening 10 structures.

Northern New Jersey is under a red flag warning until 6 p.m., meaning the region is experiencing critical fire weather conditions that “may contribute to extreme fire behavior,” according to the National Weather Service.

Active wildfires are causing growing concerns about air quality, particularly in the New York area.

On the West Coast, the Mountain Fire continues to burn in Ventura County, California, and has spread to more than 20,600 acres, according to the California Department of Forestry and Fire Protection (Cal Fire). The fire was 17% contained as of 7:25 a.m. PT and its cause remains under investigation.

Sunny and dry conditions are expected in the area on Saturday, with wind gusts reaching 20 mph. Air quality alerts are in effect across Southern California due to smoke from wildfires.