Airlines canceled more than 3,900 U.S. flights on Friday as a powerful winter storm dubbed a “bomb cyclone” rocked U.S. airport operations and frustrated thousands of vacationers, Reuters reported.

The flight cancellations come after nearly 2,700 flights were canceled on Thursday, according to FlightAware. Amtrak has canceled dozens of trains ahead of Christmas, disrupting holiday travel for thousands.

The Federal Aviation Administration (FAA) has implemented de-icing ground stops or delays at several U.S. airports due to the weather.

She said severe winter weather will have a big impact on flights, adding that flights from Boston and airports in the D.C. metro area, Seattle-Tacoma International Airport and Portland and Aspen in Colorado could also experience delays.

According to the National Weather Service (NWS), nearly 177 million Americans, or more than half of the US population, will spend the Christmas weekend under extreme weather warnings, with temperatures not seen in decades and heavy snow.

The “bomb cyclone,” as it was called in the press, will also bring very heavy blizzards, especially in the Midwestern states, according to CNN.

The cold snap could bring the coldest Christmas in decades, forecasters say. The NWS warned that more than 100 record low temperatures could be tied or broken in the coming days.