Search and book on Expedia using the following times of month or search on google flights for exact availability.
Flights departing Washington, D.C. or Boston at the end of November or early December, and return on select dates throughout December.
Flights departing New York/New Jersey in late January or mid-February, with return dates in February.
Note: WOW Airlines is a low-cost carrier. You will have to pay for each checked baggage. Please see their website for restrictions.
My sample travel dates: Jan 31 - Feb 7 (EWR-KEF-EWR)