KOCHI: India meteorological department (IMD) said southwest monsoon was likely to set over Kerala by June 4.It said conditions were favourable for further advancement of the monsoon into more parts of Arabian Sea, Lakshadweep Islands and Bay of Bengal around June 4. The upper air cyclonic circulation, which hindered the arrival of westerly winds carrying vast amounts of moisture from Madagascar, over southwest Arabian sea and neighbourhoods between 3.1km and 5.8km above mean sea level has become less marked.IMD issued an orange alert for four districts — Thrissur, Kottayam, Ernakulam and Alappuzha — on Wednesday. The remaining districts will be on yellow warning. Orange and yellow alerts will continue across the state till June 6.Rain or thundershower is most likely at most places in Kerala and Lakshadweep till June 8. As squally weather with wind speed 40-50kmph gusting to 60kmph is likely along and off Kerala, Karnataka, Lakshadweep and adjoining Maldives, IMD advised fishermen not to venture into these sea areas till June 6.Meanwhile, state received only 11.6mm rainfall against the normal of 27.7mm in the first two days of June.