The Hong Kong Observatory cancelled the cold weather warning at 9.30am today.

It had been in effect for 594.5 hours - since January 24 at 3pm. This is the longest the warning has been lasted since the alert was introduced in mid-December 1999. The second-longest record dated back to 2004 when the warning had been effective for 204 hours, 45 minutes - from January 18 to 27.

The recent long cold spell was a result of the cold air from Siberia moving south to central and southern China, while moist air was transported from the South China Sea and even as far as the Indian Ocean. This resulted in incessant cloudy, rainy and cold weather over the region.

At the same time, sea-surface temperatures over the central and eastern tropical Pacific had been persistently cooler than normal since last autumn, and a La Nina event was established in January. Figures show when a La Nina occurs during winter seasons, there is a higher chance of normal or below-normal temperatures in Hong Kong.

Today's forecast calls for the winter monsoon over southern China to moderate gradually. The temperature will range from 14 to 19 degrees Celsius with some sunny periods in the next two days. A moist easterly airstream will affect the south China coastal areas towards the weekend, bringing mist with a few rain patches.

The Observatory keeps a close watch on the local temperature changes. It issues warnings whenever Hong Kong is threatened by cold weather to alert the public to the danger of low body temperature.