With haze occurring on most days in January, the number of hours of reduced visibility observed at Hong Kong International Airport reached 449 hours (about 60 % of the time) in the month, the second highest for January since 1997.

January was warmer than normal, with the mean temperature of 16.4 degrees Celsius being 0.6 degrees higher than normal. The monthly rainfall of 16.3 millimetres was 7.1 millimetres less than normal. 

Cold surge

It was mainly fine and hazy on the first four days of January. A cold front moved across the south China coast on January 5. Under the influence of the northeast monsoon, the weather turned cold and dry on the following four days. The minimum temperature dropped to 8 degrees on January 7, the lowest in the month.

The temperature rose gradually on January 10 and 11 as the northeast monsoon weakened. It was fine and mild over the next five days.

When a maritime airstream set in on January 17, the weather became humid with morning mist. Misty conditions continued in the ensuing two days, and the visibility in the harbour once fell below 2,000 metres on January 19.

Rainy days

Another cold front reached the South China coast on January 20, bringing some rain to the territory for two days. It was cold and generally cloudy from January 21 to 24. The weather turned milder on January 25 and 26 as clouds dispersed to give some sunny periods.

A cloud band over the northern part of the South China Sea gradually extended to cover the South China coastal areas on January 27. It was overcast and cool with occasional rain on January 28.