When is it cold in Malaysia?

The easy answer is: never

Malaysia is close to the equator, therefore a warm weather is guaranteed. Temperatures generally range from 32°C/89.6 ºF at noon to about 26°C/78.8 ºF at midnight. But like most Southeast Asian countries, Malaysia's sun-shining days are interrupted by Monsoon season from November and February every year, and night temperatures can hit a low of about 23°C/73.4 ºF on rainy days.

Temperatures tend to be cooler in the highlands, with the likes of Genting Highlands,Cameron Highlands and Fraser's Hill having temperatures ranging from about 17°C/62.6 ºF at night to about 25°C/77 ºF in the day. Mount Kinabalu is known to have temperatures falling below 10°C/50 ºF.