Bali is a genuine all year round holiday destination, with hundreds of thousands of tourists coming every month to experience the spectacular scenery, fascinating culture and the friendliness of the Balinese. At any time of the year you are likely to have long periods of sunshine, and short periods of rain.
Bali is though split into a number of seasons.
Generalising hugely there is a dry season in Bali which runs from April to November, and then there is a wet season from December to March.
Having said that there are large regional differences between areas of Bali as well, with Ubud (where Villa Kalisha is located) and the central area of Bali (Kintamani/Bedugul) tending to be wetter throughout the year, and the Bukit/Jimbaran areas (where Villa Leana, Villa Amanie and Villa Champa are located) and East Bali are (where Villa Talia Vashti and Villa Anjani are located) tending to be dryer throughout the year. The North Coast of Bali can be almost arid during the peak of the dry season. Villa Kalisha is also unusual in that it is at a significantly higher altitude than central Ubud, and so is four or five degrees cooler than the normal Bali temperatures, making it a lovely warm 24 degrees C or so all year round.
Also there is a big increase in visitor numbers to Bali in July/August (which is in dry season) and Late December/January (which is in wet season), however this only really affects Seminyak/Jimbaran and central Ubud and it is really never crowded at the more relaxed and laid back locations in East Bali (where Villa Talia Vashti and Villa Anjani are located) and also Villa Kalisha has a lovely secluded jungle location that is away from the crowds.
Finally there are also spectacular ceremonies and festivals throughout the year in Bali, including Nyepi/Ogoh-Ogoh (when huge statues of devils and demons are paraded through the streets and then set fire to) as well as Galungan and Kulungan. As the Balinese calendar is different to the normal Roman calendar used in the West, these festivals are on different dates every year, and every village and town has its own ceremonies as well. The spectacular funeral processions and ceremonies for which Ubud is famous for, tend to occur during the dry season however. on top of that there are a huge list of more modern events taking in everything from marathons to art, to books to rugby.
If you were to ask our personal views, although we visit Bali all year round, we tend to plan big family trips to Bali in April/May/June or September/October/November as to us these months have the best balance of weather, crowds and therefore prices, but as I said up at the top, really any time of year you can have a great trip to Bali with or without kids.