The monthly horizontal thermal advection in the upper 250 m of the water column at ocean weather station (OWS) November was calculated by means of a divergent heat budget equation. This station is located on the southern boundary of the transition zone separating the subarctic and subtropic water masses. Bathythermograph data from 1962 to 1970 indicate that thermal advection occurs as surges of cold water across this front at intervals of 7--8 months with a duration of 3--4.5 months. Salinity data from 1968 to 1970 show a significant decrease (approximately 0.12% at 200 m) and a subsequent increase concurrent with each cooling and heating trend, respectively. Evidently, cool, low-salinity subarctic water replaces the normally warm, salty subtropic water of OWS November in periodic but nonseasonal surges.