When to go
The weather in Malaysia is tropical, so it is hot and humid almost all year round. The best time to visit Georgetown is during the dry season between November and March. The remaining months are classed as the rainy season. During the rainy season there are regular heavy downpours, storms, and showers, although they are often short. After the rain, it usually dries out quickly, so you can still get out and about without too much disruption. The humidity levels at this time, though, can be incredibly high. Baby powder is a good way to try and feel a bit more comfortable in the sticky heat.
So, go to Georgetown between November and March for the driest weather but don't be put off visiting at other times throughout the year.