Zanzibar: When to go
Powdery white sands and crystal clear waters

The best time to go to Zanzibar is between July and October. During this time, it doesn’t rain much, the temperature stays generally between 25-26ºC and it’s pretty dry in terms of the humidity. Night time breezes stave off the heat of the day. There are also fewer tourists than in January, for example, so for somebody who likes their holiday privacy, it is a great time to come.
The months between November and March are also good times to get your self going on a holiday to Zanzibar Island, although the short rains come at this time and it is quite hot and humid. Added to this is the Muslim festival of Ramadan which this year (2009) will fall between December and January. Ramadan is the longest holiday in the religion of Islam, in which Muslims fast during the daytime for an entire month. This festival moves back a couple of days every year, so be sure to check here again if you plan on going to Zanzibar a couple of years down the line. Most local restaurants, bars and discos are closed during this period. All resort and accommodation entertainment is still open though.
If you are planning to go to a resort, this is a fantastic time. Between April and June is considered the quiet season to go to Zanzibar Island. The long monsoon rains pour down. It does not rain the whole day every day, but you will have to remain indoors for some time when they come down. If you are on a budget trip, then this is the best time in terms of price, unfortunately. Many resorts are closed though during this period, so you will have a smaller selection of places to stay.