Rainfall Distribution

The seasonal wind flow patterns coupled with the local topographic features determine the rainfall distribution patterns over the country. During the northeast monsoon season, the exposed areas like the east coast of Peninsular Malaysia, Western Sarawak and the northeast coast of Sabah experiences heavy rain spells. On the other hand, inland areas or areas which are sheltered by mountain ranges are relatively free from its influence. It is best to describe the rainfall distribution of the country according to seasons.

Seasonal Rainfall Variation in Peninsular Malaysia

The seasonal variation of rainfall in Peninsular Malaysia is of three main types:

(a) Over the east coast districts, November, December and January are the months with maximum rainfall, while June and July are the driest months in most districts.

(b) Over the rest of the Peninsula with the exception of the southwest coastal area, the monthly rainfall pattern shows two periods of maximum rainfall separated by two periods of minimum rainfall. The primary maximum generally occurs in October - November while the secondary maximum generally occurs in April - May. Over the northwestern region, the primary minimum occurs in January - February with the secondary minimum in June - July while elsewhere the primary minimum occurs in June - July with the secondary minimum in February.

(c) The rainfall pattern over the southwest coastal area is much affected by early morning "Sumatras" from May to August with the result that the double maxima and minima pattern is no longer discernible. October and November are the months with maximum rainfall and February the month with minimum rainfall. The March - April - May maximum and the June -July minimum are absent or indistinct.

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