Last month was Hong Kong's hottest November on record with a mean temperature of 23.2 degrees Celsius, weather scientists said yesterday. And this year is on course to be the hottest since records began. Yesterday, ferry travellers also had to contend with unseasonal mists when visibility in the harbour fell to 1,200 metres in conditions a Hong Kong Observatory spokesman described as unusual but not rare for December. The fog also reduced visibility at the airport to 4,500 metres. The Observatory reported just six foggy December days in the 53 years since the end of World War II. However, the fog was not pollution-related and did not appear to indicate a new seasonal pattern, since four occurred in the 1940s and 1950s. The last one was in 1992. The Observatory spokesman said the winter monsoon over southern China had been weaker than normal. In the absence of a significant monsoon, a moist easterly airstream had brought humid and misty weather. The mean minimum temperature of 21.4 degrees last month also was the highest on record. The mean temperature from January to November reached 24.4 degrees. The Observatory said 23.5 degrees was the norm for the first 11 months of the year. Cooler weather is forecast from tomorrow.