Hong Kong has sloshed its way through the wettest April since records began more than a century ago, the Observatory said yesterday. The downpours that halted traffic and submerged parts of the New Territories were caused by unusual weather patterns which dumped almost 548mm of rain over the month. The Observatory said the figure was more than three times the average for the month. Much of the drenching came on one day, April 23, when as much rain fell in 24 hours as usually falls in the entire month. In the year's first black storm warning, 172.5mm of rain bucketed down that day, leaving Sai Kung residents to wade through knee-deep water to reach home. It was the second-highest single day's rainfall for any April since records began. The Observatory said the average monthly count for April was 161.5mm. A landslide closed Clear Water Bay Road to traffic for several hours, and two cars in Western were damaged when a tree fell on them. More than 60 cases of flooding were reported across the SAR. The Drainage Services Department said the system was overwhelmed by the freak conditions, and eight temporary shelters were opened for residents unable to go home because of flooding. 'April 2000 was marked by unsettled weather and heavy rain due to the frequent passages of troughs of low pressure and a very active southwest monsoon,' an Observatory spokesman said. He said the soaking started on April 2, when a trough of low pressure over much of southern China brought thunderstorms. Unsettled weather continued to bring rain for the next few days, then there was a reprieve of about a week, when conditions remained damp and drizzly. Strong southwesterly winds on April 14, however, saw a return of stormy weather, dumping more than 500mm of rain in the western New Territories. 'Villages were half-submerged in flash floods and water was about a metre deep,' the spokesman said. 'There were 128 reports of flooding and 28 landslides. More than 200 hectares of farmland and 35 hectares of fish pond were inundated.' A week later, there were more storms, with three days of heavy rain culminating in the April 23 drenching. The Observatory said total rainfall in the first four months of the year amounted to 686.5mm - more than double the normal figure of 299.8mm and the third-highest level reached in that period since records began. Four red and one black rainstorm warnings were issued in April, the earliest since the warning system was introduced in 1992. The red signal means heavy rain could cause serious road flooding and traffic congestion, and may affect schools and public examinations. The black signal means that there are major disruptions and bad weather. Temperatures were higher than usual last month, averaging 23.1 degrees - 0.9 degrees higher than the monthly mean. April's wet conditions spilled into this month, with floods just a week ago bringing motorists to a standstill on parts of Hong Kong Island. Observatory spokesman Au Chin-hang said the wet start to the year did not necessarily mean Hong Kong should expect a year-long soaking. 'Based on climatology, we don't expect the total rainfall in 2000 to deviate significantly from the normal [annual average] of 2,214.3mm.'