Polynyas accelerate oceanic and atmospheric processes. We additionally think polynyas influence biological activity. We pursued daily transition of coastal polynyas in the Antarctic Peninsula area from 1978 through 1995 using images of sea ice concentrations by the satellite microwave observations. A typical polynya existed off the tip of the Peninsula in 1987 and 1991. In the such years, sea ice cover developed extensively. Inversely, the years of the narrow sea ice cover were 1988, 1989,1990 and 1993. In the such years, polynyas did not existed. The typical polynya (nearly 500 x 200 km) in 1987 was pursed from beginning on August 1 to end on October 20. The shape of the polynya changed remarkably in several days. We speculated that annual variability of sea ice cover and consequently polynyas is mainly caused by the Westerly winds.