The Hong Kong Observatory on Monday issued the red rainstorm warning at 12.20pm.

The forecaster said an active southwest monsoon combined with an upper-air disturbance is generating heavy showers and squally thunderstorms affecting the coast of southern China and the northern part of the South China Sea.

It warned that further heavy rain could cause, or may have already caused, serious road flooding and significant traffic congestion.

The public is strongly advised to stay away from watercourses due to the threat of flash floods. Residents living near rivers are urged to remain highly vigilant, monitor weather conditions closely and consider evacuating if their homes face imminent flooding risks.

In response to the severe weather, the Education Bureau announced that all afternoon classes are cancelled. Schools already in session are instructed to continue operating until their normal dismissal time but must ensure conditions are safe before allowing students to return home.

Regarding evening classes, it said that if the amber rainstorm warning is issued or if all rainstorm warnings are cancelled at or before 5pm, evening school classes will proceed as usual tonight unless further announcements are made.

The Social Welfare Department confirmed that all units providing specific services will remain open during their normal operating hours. This includes child care centres, services under the Neighbourhood Support Child Care Project, after-school care programmes for pre-primary or primary school children, elderly services centres, day pre-school rehabilitation services units and day rehabilitation units.

Additionally, the Home Affairs Department has opened temporary shelters for people requiring temporary accommodation, and its emergency coordination centre is now operational.

Meanwhile, the Labour Department issued a reminder to employers, urging them to establish clear work arrangements for staff in advance concerning reporting for duty, release from work, resumption of work, and remote working options during and after rainstorm warnings or extreme conditions.

It emphasised that these proactive measures are essential to ensure employee safety, maintain smooth organisational operations and foster good labour-management relations.