Planning for the weather is an important factor for making your trip to Sematan a success, especially when youโre splurging. The hottest months are usually May and June, with an average temperature of 27ยฐC, while the coldest months are February and January, with an average of 26ยฐC. The rainiest months in Sematan are December, January, November and October, with each month seeing an average of 375 mm of rainfall.