On Ls = 340¿, first Mars year of Viking on the surface, a local dust storm was observed at the Viking Lander no.1 site by Viking Orbiter A. The storm lasted less than one martian day (sol) with the dust raised affecting the site for about three sols. It is concluded that this storm was caused by baroclinic waves and that the threshold wind speed for saltation was 25--30 m sec-1.