Climate

Malaysia is blessed with perpetual sunshine. Lying entirely in the equatorial zone, its climate is governed by the seasonal North-East and South-West monsoons. Of the two, the south-west monsoon which cycle from mid-November till March serves as a drier period for Malaysia, particularly for the west coast of the Peninsula as it is sheltered by the land mass of Sumatra. During the North-East monsoon, from May to September, the sky turns grey, the landscape is drenched and the rivers become swollen. The transitional period between the two monsoons is marked by heavy rainfall, accompanied by lightning and thunderstorms.

Malaysia’s share of annual rainfall of about 260 centimetres is above the global average. Sarawak records the most rainfall in the country, receiving between 350 to 500 centimetres annually. Basically, there are three main types of rainfall: convectional, orographic and cyclonic, the first being the most prominent.

Daytime temperatures in the lowlands average 32 degrees Celsius (86 degrees Fahrenheit) with high humidity levels of 80 per cent on most days. However, for every 100 metres increase in altitude, the temperature drops by about 0.6 degrees Celsius. The only place where freezing point is experienced is at the peak of Sabah’s Mount Kinabalu, the highest mountain in Southeast Asia.


*thunderstorms:
The early stage of a storm’s development can be traced to the cauliflower like clouds known as cumulus which are formed by contraction in the early part of the day. As they grow bigger, developing into the cumulonimbus, they become laden with rain water which is released in a sharp shower in the late afternoons. Malaysia is out of the way of typhoons and cyclones which miss it by several hundred kilometres. On one occasion, however, in the early hours of 26 December 1996, the west coast of Sabah woke up to the violent lashing of tropical storm Greg.

**convectional, orographic and cyclonic:
Convectional rain is caused by the rising of warm moist air following its contact with the surface of the earth. As the pockets of air breach the condensation level, they become thunder clouds or cumulonimbus some of which can reach 10 kilometres in height. A day that starts off bright and sunny in the morning can suddenly change in the late afternoon. Overcast skies and a heavy downpour lasting between 1 to 2 hours take over, accompanied by strong winds and sometimes flash floods that cause damage to vegetation and property.

Orographic rain falls mainly along the windward side of mountains, notably the Titiwangsa Range that forms the backbone of Peninsular Malaysia. The highlands in Sabah and Sarawak also receive their fair share of orographic rain which is spilled by water laden clouds as they rise above the condensation level in the attempt to cross over a mountain.

Cyclonic rainfall, which can pour continuously for days on end, is one of the major causes of floods in Malaysia. Most of it falls during the north-east monsoon period and covers a wide area along the east coast of Peninsular Malaysia as well as coastal areas in Sarawak. It is caused by the collision between the easterly and the westerly trade winds that results in the ascension of moist air into the atmosphere and condenses into rain.