The government on Thursday announced a series of measures intended to help Hong Kong cope better with extreme weather, including new arrangements for MTR services when the second-highest typhoon signal is in force.

Trains on overground sections of the network will continue until the end of the line, or at least to a large station where passengers can take shelter, instead of only stopping at the next station when the No 9 typhoon signal is in force.

Last year, scores of travellers were left stranded at the the airport when Typhoon Koinu forced the suspension of the Airport Express and all bus services.

"In case the train is already in this open section, we will try to reach the final destination as far as practicable and safety permitting," Transport Secretary Lam Sai-hung said at a cross-departmental press conference.

"If not, we're now planning to stop at a major station in which that station may be big or may be connected to the mall or other commercial areas so that people or passengers could have a better place for shelter so that they can depart the area when the weather allows."

Meanwhile, Undersecretary for Security Michael Cheuk warned that people who deliberately and repeatedly put themselves in jeopardy during extreme weather may face fines or even prison.

Cheuk gave the example of people going onto beaches that are closed, adding that the risk is simply not worth it.

"What we're aiming to do is dissuade people from having some sort of high risk, very risky activities. If anything happens, it's not just costing them HK$2,000 or 14 days in prison. It will cost their life. It's also endangering the life of my emergency response officers. So what we're saying is do not do something dangerous. Do not put yourself at risk," he said.

Cheuk also said the observatory will issue advice and warnings to members of the public during adverse weather, adding that a city-wide SMS alert system is only reserved for "unforeseen situations" such as tsunamis.

Asked about arrangements when water is discharged from the Shenzhen Reservoir, officials said they will alert Hongkongers as soon as authorities across the border start considering such a move.