Over the Northeast Newfoundland Shelf the main source of ice is advection from the north by winds and currents. Using historical ice charts, it is shown that the advance of ice is limited by ice melt throughout the winter months when the ocean provides the only source of heat, part of which is lost to the atmosphere and part of which goes to melting ice. Following techniques developed by Maykut (1978, 1982), the vertical growth of sea ice south of 55 ¿N is examined in terms of the net heat loss from the ocean (Fw) and the conductive heat flux (Fc) through the ice to the atmosphere. Fc is estimated by assuming a linear temperature gradient through the ice from the freezing point of seawater at the underside of the ice to the surface temperature, calculated by solving the radiation balance at the ice surface using monthly climatological data. The flux Fw is estimated from monthly averaged temperature profiles from station 27 off St. John's. Newfoundland, in the south and from historical data from the Labrador Shelf in the north. The results suggest that in the north, over bare ice, growth of approximately 1 cm/d might be sustained off Hopedale (55 ¿N) for December through March, while in the south off St. John's and estimated melt rate of 5 cm/d can be sustained throughout the winter months. Growth rates are strongly dependent on the depth of snow cover and the fraction of open water. The flux Fw reaches 250 W m-2 at station 27 in January, and it is suggested that much of this heat is derived from summertime heating when the whole of the Northeast Newfoundland Shelf is ice free.