Bali location is south of the equator Bali can be considered a real tropical island with an average temperature of 22ºC in the mountain regions and up to 30ºC along the coast.
Bali has two seasons: the wet season (monsoon) and the dry season. During the monsoon the humidity level can reach 97%. So you can imagine that if you add the high temperature to the high humidity it can become a sweaty situation. Sometimes thought it was even pretty chilly in the evening while staying around Ubud and make sure you have some warm clothing with you too while travelling in the mountainous areas of Munduk and Batukaru.
Theoretically the monsoon starts around the end of October and lasts until April. But in reality the rain can come later or it can keep on pouring well into May. Generally the best time to go is from May to September. But still expect some tropical rain spells during this time, especially in the mountains. The good thing about it though is that the rain can fall from the sky with buckets of water at once and often stops within an hour leaving a refreshing scent everywhere.
The Imprtant thing is about Indonesian Currency
The currency of Indonesia is the Rupiah, usually marked as Rp or IDR. Indonesia is still very much a cash-based society, and credit cards are still not accepted in many places.
Coins start at Rp100 up to Rp500
A bronze Rp500 is slowly disappearing. There is also now a new Rp1000 coin:
It may eventually replace the Rp1000 banknote, though at the moment it is relatively rare.
Banknotes come in denominations of Rp1000 up to Rp100 000:
The ABCs of Indonesian ATMs
JUST THE FACTS
Almost all Indonesian ATMs are connected to the Maestro/Cirrus network, and provide the choice of English or Indonesian instructions.
Most ATMs dispense Rp50 000 notes (about $US6), although some give Rp100 000 (about $US12) notes. It is usually marked whether it is Rp50 000 or Rp100 000. If possible, avoid the latter unless you are e.g. about to buy something expensive. If you want to minimise transaction fees, get the maximum amount: Rp1 250 000 ($US140) for the Rp50 000 ATMs, Rp2 500 000 ($US280) for the Rp100 000 ATMs. In regional and remote areas, the most common bank is BRI (pronounced “BAY UR EEE”), but not all branches have ATMs.
In smaller cities, you might also find an ATM that dispenses Rp20 000 notes, up to a maximum of Rp500 000 ($US60) per transaction.
Source : http://flights.indonesiamatters.com/1899-idr-visitors-guide/
http://www.bali-travel-life.com/bali-travel-tips.html