The downpour dumped more rain on Hong Kong than on any day since 1926. Observatory records show the highest daily rainfall was 534.1 mm on July 19, 1926, and the second-highest was 520.6 mm on May 30, 1889. By 11 pm yesterday, 410 mm had fallen - the most in a single day in June. Meteorologists said the rain would continue at least until the weekend. A trough of low pressure, rather than the diminishing El Nino effect, was to blame. Observatory scientific officer Edwin Lai Sau-tak said: 'The El Nino effect is forecast to end by the second half of this year, but we need long-term evidence before we can say what causes more rain.' The downpour was most ferocious between 4 am and 8 am.