Fresco is a nice option for wool suits in summer-- stays crisp and breathes beautifully. Your challenge will be to get a lighter weight (10 oz) version in the right color blue. As far as shirts, ties, etc., you could get a simple white shirt (cotton/linen if you're really worried about the heat, or cotton voile) and basic tie. But do consult local customs.
How about a light silk/wool blend three piece with a Borsalino? In perhaps a mouse grey or white. The shirt should be a light Italian cotton or if you so desire silk. However the wearing of silk shirts does create a slight difficulty in achieving a perfect tie knot. With a three-piece suit of that nature a lace pocket square of whatever color, red perhaps, would not look odd. If you wear a conventional suit a lace square would look decidely odd.
(LabelKing @ May 09 2005,19:38) In perhaps a mouse grey or white.
whats the rule on lighter colored suits of this type for evening wear?
Traditionally in a place like Shanghai it would have to black tie. However since it is going to be muggy, and outdoors some light colored would seem to be appropriate. Like in tropical locales with the white dinner jackets, and such. White might be too afternoon wear not that I think about it.