After classifying various water masses around the Noto Peninsula and Sado Island, Japan and identifying their seasonal variation, we investigated flow fields in the area. Distributions of flow structures and water properties were analyzed based on intensive observations using a conductivity–temperature–depth profiler during 2002–2020. Tide gauge and satellite altimetry data were also analyzed to elucidate the temporal and the more widespread horizontal variation of the sea surface geostrophic flow field. Interannual change of the northeastward baroclinic jet formed offshore of the Noto Peninsula in fall was found. Furthermore, anticyclonic eddy formation around Toyama Bay which is part of the current path transition of the coastal branch of the Tsushima Warm Current was found to result from effects of bathymetric change behind the Noto Peninsula. At that time, the sea-surface current speed of the coastal branch was also high. We propose new methods for predicting current path transition events two weeks in advance.