Because of a seasonal reversal in wind direction, areas with the monsoon type of climate experience different air masses in different seasons. Naturally this has important effects on the precipitation and temperatures of the monsoon regions. Most of these regions have wet summer and dry winter.

During summer the tropical as well as middle-latitude monsoon regions are under the dominance of the tm (tropical maritime) air masses which are full of moisture. Contrary to it, during winter the dry, cold and stable air masses of continental origin dominate such regions.

Remember that the dry and stable air mass controlling the winter circulation in the tropical regions is associated with the subtropical anticyclone and is not so cold.

However wherever there is a large expanse of ocean in the path of the winter monsoon, before reaching a land area the air picks up large quantities of moisture from the water surface and there is heavy rainfall.


For instance, the eastern Philippines, the eastern coastal regions of Peninsular India and the western Japan receive heavy precipitation during the winter monsoon period.

In the middle-latitude monsoon regions the summer monsoon brings with it tropical heat which raises the summer temperatures.

On the contrary, the winter monsoon circulation brings in sub-polar cold air which makes the winter abnormally cold. Thus, the annual range of temperature is naturally very high in these regions.