Bali has such a mild and agreeable climate the wholer year round. The sunny days within dry season between May and September are warm and pleasent, while rainy season between October and April, tropical showerwill alternate with clear sky and sunshine. The average temperature of the day in coastal areas varies from about 28^o C (82^o F) during May, June, July to about 30^o C (86^o F) in March and October. 

It is approximately one and half hours drive to the highland where temperature varies from 16^o C to 26^o C and it is known to drop about 8^o C during the night. 

The humidity is high (from a minimum of 70% to a maximum of 96%). The weather is most pleasent between May to September. 
 

Source : Bali, Guide Book