Monsoon is likely to get a boost with a change in atmospheric conditions in the next two days to hit the Kerala coasts, the weather office said on Monday.  The India Meteorological Department (IMD) said monsoon had advanced into the southern-most parts of the Arabian sea, some more parts of Maldives-Comorin area, southwest, southeast and east coast of the Bay of Bengal. IMD had earlier forecast that monsoon would hit the Kerala coast on June 6, later than the normal date of June 1.  “An east-west shear zone at 3.1 km above mean sea level is very likely to develop across extreme south peninsula from June 5 onwards, leading to favourable conditions for onset of Southwest Monsoon over Kerala,” the IMD forecast said.  Thunderstorms and bouts of heavy rain, which are likely to lash parts of Kerala, Tamil Nadu and Karnataka in the next 2-3 days ahead of the onset of monsoon, would hardly have any impact on heat waves sweeping across northern, central and western parts of the country.