SINGAPORE: Flash floods may occur in Singapore between Friday (Jan 10) and Monday due to a monsoon surge. A monsoon surge refers to a strengthening of winds over the South China Sea, causing extensive rainclouds to form over our surrounding region. The monsoon surge is forecast to bring rainy and windy weather to Singapore over the next four days, the National Environment Agency (NEA) said on Thursday. Periods of moderate to heavy thundery showers with cool and windy conditions can be expected.