The Observatory on Tuesday said it would issue the Standby Signal No. 1 this evening and there was a relatively high chance it would issue the Strong Wind Signal No. 3 later this week.

Forecasters said the number one signal was scheduled to be issued sometime between 5pm and 8pm on Tuesday, as Tropical Cyclone Yagi was expected to remain more than 600 kilometres away from Hong Kong and wasn't expected to directly affect the SAR yet.

"With Yagi edging closer to the coast of southern China gradually, winds will strengthen over the region later this week. The chance for issuing the Strong Wind Signal No. 3 is relatively high," the Observatory said.

It said it expected heavy squally showers and rough seas with swells, as the weather for coastal Guangdong was expected to worsen in the latter part of the week.