Malaysia is a tropical country; therefore, the weather stays the same through out the year. The temperature stays between 22 degree Celsius to 34 degree Celsius and it rains almost everyday. The usual weather is hot and humid during the day but surprisingly pleasant in the evening.
Cotton clothing is the most apt kind of clothing to move around in although all classes, buses, taxis, malls, etc are air conditioned so you might want to carry a shrug with you.
A word from the wise, Always carry an umbrella, a sun block (SPF 30) and a bottle of water with you. The sun can get harsh and the rainfall is unpredictable. Due to the humid weather, you might not feel necessarily thirsty but it’s good to stay hydrated in order to avoid dizziness and dehydration.
If you don’t want people to faint in buses or trains while you’re traveling with them after a long day in the sun, use a deodorant!