Cloud cover
Sibu has a tropical rainforest climate according to the Köppen climate classification. The Sibu town has high temperatures of and low temperatures of . Annual rainfall is approximately , with relative humidity between 80 and 87%. Sibu receives between 4 and 5 hours of sunlight per day with yearly average daily values of global solar radiation of 15.2 MJ/m2. Cloud cover over Sibu reduces during the months of June and July (6.75 Oktas) but increases from November to February (7 Oktas).