Analysis of archival satellite images of sea surface temperature from May to September 2010 allowed determining the features of the synoptic variability of these frontal zones. It is shown that the regions where extreme values of the sea temperature gradients and surface fronts occur occupy a significant sea area near the middle position of the frontal lines. In Dvinskiy Bay, this region occupies almost two thirds of the bay’s water area, and the displacement of the runoff front in its western flank reaches 70 km per month. All the fronts undergo the largest displacements in the first half of the warm season under the influence of synoptic processes and river runoff against the background of insufficient heating of the upper layer, but their high dynamic activity persists later, manifesting itself in the form of the formation of tongues and meanders up to several tens of kilometers. The greatest variability of the temperature field in the form of perturbations of the frontal section is demonstrated by the Gorlo frontal zone. This dynamics is an important element of water exchange in the strait.