First tell rain apart from a typhoon
Ordinary rain just changes your route; a tropical cyclone or rainstorm signal affects sailings, cross-border transport and some attractions. In typhoon season, check the official weather bureau and the ferry or checkpoint notices each morning, and be ready to spend an extra night.
The Cotai main drag: a day without an umbrella
Venetian, Londoner and Parisian are joined by indoor or covered links, and with the Grand Canal Shoppes that is a full day. Keep shows, meals and shopping on one side; do not cross in the rain for a single shop on the other.
Indoor options on the peninsula
If you would rather not cross to Cotai, the peninsula has fallbacks: library and exhibition spaces, the covered courtyards of the Mandarin’s House, the roofed Red Market, the science centre. Downgrade the heritage leg to the arcades and shopfronts along the avenue, where at least there is something over your head.
The small practical things
Carry a folding umbrella rather than a long one — it stows better in halls and on buses. Wear soles with tread; both the steps and the tiled floors get slippery. Taxis are hard to find in rain, while buses and resort shuttles keep running. Order your day by what is covered, not by what you fancy.