The Weather of November 2015

    November 2015 emerged as the warmest November in Hong Kong since records began in 1884 with a record-breaking mean temperature of 24.0 degrees, 2.2 degrees above the November normal of 21.8 degrees. The anomalously warm weather was mainly attributed to the relatively high sea surface temperatures over the northern part of the South China Sea and the rather weak advection of cold air from the north despite the prevailing northeast monsoon. The month was also drier than usual with only 22.8 millimetres of rainfall, a deficit of about 39 percent as compared to the normal figure of 37.6 millimetres. The accumulated rainfall of 1810.2 millimetres since 1 January was about 24 percent below the normal figure of 2371.7 millimetres for the same period.

    Under the influence of the northeast monsoon, the weather in Hong Kong was mainly fine but appreciably cooler on the first two days of the month. With the setting in of an easterly airstream over the coast of Guangdong, the weather was a mixture of cloudy days, sunny periods and some light rain patches for the next five days. With the clouds thinning out gradually, there was more sunshine on 8 and 9 November, and the weather became warmer with temperatures at the Hong Kong Observatory rising to a maximum of 30.3 degrees, the highest of the month, on 9 November.

    Meanwhile, a cold front over inland Guangdong moved southwards and crossed the coastal areas on the night of 9 November. A strong northeast monsoon associated with the cold front brought windy and slightly cooler weather with rain patches to the territory over the next four days. After a brighter day on 14 November, the setting in of a fresh to strong easterly airstream over the coast of Guangdong brought windy conditions again with more rain patches on 15 and 16 November.

    The weather turned generally fine apart from some coastal mist patches on 17-18 November. Windy and mainly cloudy conditions returned with an easterly airstream for the ensuing three days, before clouds thinning out gradually and fine weather setting in on 22-24 November.

    An intense northeast monsoon reached the coast of Guangdong on the morning of 25 November and winds strengthened gradually form the north that day. While the weather remained mostly fine under the dominance of a dry continental air mass, it became appreciably cooler as temperatures at the Hong Kong Observatory fell to a minimum of 15.3 degrees, the lowest of the month, on the morning of 27 November. With the moderation of the northeast monsoon, temperatures recovered gradually towards the end of the month.