Planning for the weather is a good way to make your trip to Sungai Petani relaxing and enjoyable, especially when you’re splurging. The hottest months are usually March and February with an average temp of 81°F, while the coldest months are January and February with an average of 79°F. The rainiest months in Sungai Petani are November, October, May, and September, with each month seeing an average of 12 inches of rainfall.