Bali weather can be rainy sometimes. But if you want sunny weather, you can go to the neighboring islands: Nusa Penida, Nusa Lembongan and Gili, where sun shines almost eveyday with clear skies, hot sand and clear blue water.
Nusa Penida Island is close to Bali but the atmosphere is very different and the island is usually much hotter. During the day it's quite hot: the temperature is about 31 degrees during the day, and at night it drops to 24. Water temperature variates around 28 degrees. The average rainy days per year is 22, a number way below the neighboring island of Bali.
The weather in Bali differs form the weather in Nusa Penida, even though it sometimes rains in Bali, Nusa Penida is still sunny and hot. So, regarding weather, it can be said that there is no need to worry if you want to travel to Nusa.