Hong Kong is expected to be hit by hail on Thursday afternoon, according to the weather forecaster, with a second tropical depression moving towards the city predicted to intensify into a super typhoon next Tuesday.

The Observatory said two storm formations were entering the region, with the further one located about 2,240km (1,392 miles) east-southeast of Hong Kong on Thursday morning as the city sweltered and the No 1 typhoon standby signal, issued the previous night, remained in force.

“The tropical cyclone over the western North Pacific to the east of the Philippines will intensify significantly and move towards the vicinity of the Luzon Strait in the next few days,” the weather forecaster said.

The Observatory predicted that the cyclone could gradually intensify into a super typhoon at about 600km away from the city on Tuesday, with wind speeds at its centre as high as 185km/h (115mph).