Did a quick check using the Wyoming balloon trajectory prediction website. Results aren't great. If you launch from say Jurong Island, it'll land about 93km away in the Straits of Malacca on the Indonesian side. Launching from say Pulau Ubin is even worst, it'll over fly both Singapore and Malaysia and still in the Straits albiet closer to Malaysia. These courses are predicted based on current prevailing winds of course.
Check out that website and ask to load using Google Earth KML, it'll show you the prediction.
http://www.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html <- Convert the lat and long to decimal degrees if you need it.
So it would appear that April and October are probably the best months for launching. Think I'll check the prediction again next month to see.Originally Posted by NEA