‘Major Cold’: Intense winter monsoon to bring three days of chill after Jan 20

Hong Kong is set to experience a sharp drop in temperatures next week with the arrival of an intense winter monsoon, with a three-day cold spell expected to begin on Jan 20, a date that coincides with “Major Cold,” the last of the 24 solar terms on the Chinese lunar calendar which marks the coldest time of year.

The city will first enjoy mild and dry weather through the weekend and into early next week, with daytime highs of around 22 to 23 degrees Celsius. However, an intense winter monsoon is forecast to reach southern China in the middle of next week, triggering a sudden and significant cooling trend across the region.

The Observatory said a dry northeast monsoon will continue to bring generally fine weather to Guangdong from later this week into early next week, with warm daytime conditions but relatively large differences between day and night temperatures. Under this pattern, minimum temperatures between Jan 15 and Jan 19 are expected to range from 17 to 18 degrees, while daytime highs will remain at around 22 to 23 degrees.

Conditions will change rapidly on Jan 20, when the winter monsoon arrives. The minimum temperature is forecast to fall to about 15 degrees, representing a drop of around eight degrees from the previous day’s high.

The cooling trend will deepen over the following three days. From Jan 21 to Jan 23, the Observatory forecasts minimum temperatures of around 12 degrees, with daytime highs dropping into the mid to high teens. On Jan 21, the maximum temperature is expected to reach about 17 degrees, falling further to around 16 degrees on Jan 22 and 23. The weather during this period is forecast to be mainly cloudy, with north to northeasterly winds at force 4 to 5, occasionally reaching force 6 offshore and on high ground early on Jan 21.

Temperatures in the New Territories are expected to be even lower. Most areas there will see lows of about 8 to 9 degrees, while Ta Kwu Ling could drop to as low as 6 degrees on Thursday and Friday.

The Observatory said the colder air mass will mark the most notable cold spell of the season so far, following a period of relatively mild winter weather in the city.