OKC is in plant hardiness zone 7a with an average annual minimum temperature between 0F to 5F, -14F is zone 5b, nearly zone 5a (-15 to -20), almost a full 20 degrees colder than their average annual minimum.
NYC, LGA, JFK, EWR, and ISP are in hardiness zone 7b, with an average annual minimum temperature between 5F and 10F. A cold blast of that magnitude would put us around -10F.