BEIJING / HULUDAO, Liaoning - The area of frozen sea off Northeast China is expected to increase within the next week, continuing to isolate island fishermen, weather forecasters have warned.

"The ice area at Liaodong Peninsula stretches 74 nautical miles (137 kilometers) from the coast and a strong cold front may worsen the situation between next Monday and Wednesday," said Liu Yu, chief forecaster of the National Marine Environmental Forecasting Center. On Thursday the average ice thickness was 15 to 25 cm, and possibly 40 cm thick in some areas, according to the daily report by the center.

After mid-February, the ice will gradually melt as temperatures rise, Liu added.

Yan Weiming, a 31-year-old fisherman from Juehua Island, Liaoning province, calls his two-month isolation on the island each year the "winter sleep". He and his family cannot leave the island because the coastal ice is too thick for boats to get through. Bohai Bay has turned into a massive ice rink, he said.

Temperatures in most of Northeast China in late January were about 5 C below average for the past 20 years, said Sun Jun, chief forecaster of the China Meteorological Administration. The temperature in parts of the Inner Mongolia autonomous region dropped to almost - 47 C on Jan 27. The lowest recorded, in 1966, was - 50 C.

Yan and the island's other 3,200 residents have been cut off from the mainland since Dec 30 when the ice became too thick for boats to operate.

Yan said watching TV, playing mahjong, visiting relatives and staying with families were his main activities in the two-month frozen season.

But he said some residents had found an opportunity to make money running a cargo delivery and passenger service by electric tricycle between the island and nearby Xingcheng city on the mainland. They charge up to 100 yuan ($16) one-way.

"I don't take the ride, because it's not safe," Yan said. He hopes that one day a bridge will be built connecting the island and Xingcheng.

Meantime, Yu Xibin, deputy director of Huludao maritime safety administration, said that with the help of icebreakers, tugboats and a helicopter, islanders' needs regarding food supply or medical treatment could be met in an emergency.

"A helicopter has been prepared for the island's patients to get better medical treatment from the nearby city when necessary," Yu said, adding that the island has only one hospital, which cannot treat patients with severe illness.

According to satellite images, the area of sea ice in Bohai Bay reached about 17,000 square kilometers on Monday, slightly smaller than the average over the past 24 years.

In 2010, China experienced the highest volume of sea ice in three decades with about 90 percent of Bohai Bay covered by ice, according to statistics from the State Oceanic Administration.