Last month was the warmest October since records began in 1884, with a monthly mean temperature of 26.5 degrees Celsius, 0.1 degree higher than the 26.4 degrees recorded in 1983 and 2006.

The Hong Kong Observatory said the northeast monsoon during the month was weak, resulting in cooler air failing to reach the south China coastal areas.

The 1971-2000 climatological record shows there are on average about six days with a minimum temperature of below 22 degrees in October. However, not a single day this October was below 22 degrees.

The record-breaking temperature also reflects to a certain extent the long-term warming trend in Hong Kong, the observatory said. The monthly mean October temperatures in the past 50 years showed a rising trend of about 0.2 degree each decade and half of the 10 warmest Octobers occurred in the past decade.