Hong Kong's first frost of the winter was recorded yesterday as the cold weather caused by a winter monsoon affecting southern China persisted. The Observatory said frost was reported on the public golf courses on Kau Sai Chau near Sai Kung yesterday morning. Yeung Kwok-shung, a scientific officer at the Observatory, said the report was received at about 8am while the lowest temperature in Sai Kung was 9 degrees Celsius. He said the temperature near the grass on the golf courses was probably lower, making frost possible. The Observatory cancelled the frost warning at 9.45am, but reissued it again late last night. The warning covers the northern New Territories. It said the previous frost report for Hong Kong was recorded at Kau Sai Chau last January 30. Mr Yeung said the weather would become warmer towards the weekend, but mornings and nights would remain quite cool. Two sick elderly men died during yesterday's cold weather, but it was unclear whether their deaths were linked to the drop in temperature. The first case involved an 87-year-old man surnamed Lau, who was declared dead at his flat in Tin Shui Wai. About two hours later, an 82-year-old man surnamed Mok was found unconscious at his flat in Mong Kok and taken to Kwong Wah Hospital, where he was later declared dead. The cold weather brought a sharp rise in the price of vegetables, with frost on the mainland causing a drop in supply. Edward Lai Kwok-yan, general manager of the Vegetable Marketing Organisation, said the wholesale price for vegetables had risen by about 25 per cent. He said frost in Guangdong, the main supplier of vegetables to Hong Kong, caused supplies to the city to fall by 10 per cent yesterday.