The Weather of December 1997

    December 1997 was warmer than normal, the mean temperature of 18.9 degrees was the seventh highest for the month. The mean minimum temperature of 17.1 degrees ranked the sixth highest for December. On the other hand, the total bright sunshine duration of 100.4 hours was 81.1 hours below normal and stood the fourth lowest for December. Furthermore, the mean monthly total cloud amount of 64 per cent was 15 per cent higher than normal.

    Although the total rainfall in December was only 6.5 millimetres against a normal of 27.3 millimetres, the annual total of 3 343.0 millimetres was 51 per cent above the normal figure and this makes 1997 the wettest year for Hong Kong on record.

    The weather was fine and warm during the day on 1 December with temperatures rising to 25.2 degrees, the highest in the month. A surge of the northeast monsoon reached the south China coast late in the afternoon and strong northerly winds prevailed offshore during the night. Winds moderated early on 3 December and the weather was mainly cloudy with some light rain patches till 7 December.

    Mist patches formed on the morning of 7 December, but were cleared by the passage of a cold front later that morning. Strong northerly winds affected local areas for two days with the dry northerly airstream also clearing the clouds. Temperatures dropped to 12.4 degrees, the lowest in the month, on 9 December. Over the northern part of the New Territories, temperatures dropped to below 10 degrees the next morning.

    It became mainly cloudy again on 11 December. Winds turned northeast on 14 December and the weather became fine with long sunny periods the next day. Winds became light on 16 December and there were mist patches the next day. Misty condition in the morning persisted for the next few days.

    Light rain patches began to affect our area on 21 December. Rain was heavy over the Peak area on Hong Kong Island and over Tung Chung on Lantau early next day when a weak cold front crossed the south China coast and cleared the mist. Rain eased off during the day on 23 December but the weather remained cloudy. It became fine and sunny on 25 December. Apart from some light rain patches on 26 December, mainly fine weather prevailed till the end of the year.

    Only one tropical cyclone occurred in the western North Pacific in the month.

    During the month, no aircraft was diverted due to adverse weather.