Hong Kong is on track to miss its average monthly rainfall total for the second month in a row, despite a torrential downpour yesterday that caused flooding in the New Territories. The amber rain warning was raised just after 9am, closely followed by the thunderstorm and flooding warning. Observatory senior scientific officer Chan Sai-tick said there had been more than 100mm of rainfall over the New Territories, which got the biggest drenching, while Hong Kong Island had seen closer to 30mm. "The bad weather was due to the trough of low pressure residing on the coast of Guangdong," he said. "Although it will bring more showers and thunderstorms, we expect the trough will gradually weaken." Read more: Catastrophic flooding could hit Hong Kong and Macau as Chinese scientists predict Pearl River Delta may rise by over a metre by end of century Read more: Thunderstorm warning issued for Hong Kong as more than 30mm of rain drenches city Chan said the weather would turn fine from this afternoon. By Sunday night Hong Kong had only recorded 53.3mm of rainfall in September, well below the monthly average of 327.6mm. Although Monday's downpour would add to that total, Chan said he expected it to still fall far short of the average. "We only expect a few showers up to September 30th and up to this point we don't expect really heavy rain to come for the rest of the month," he said. "Most likely we will have a drier than normal month for September." Chan said the low rainfall had been due to the lack of typhoons in Hong Kong this September, which was possibly a result of El Nino weather activity. "One storm can bring hundreds of millimetres of rainfall, but this month we don't have that," he said. This follows the driest August in 23 years, with only 143.3mm of rainfall falling throughout the month. The expected average is 432.2mm. The lack of rain in August was also linked to typhoon activity, as two simultaneous tropical cyclones passed Taiwan, bringing hot and clear days to Hong Kong.