The warmest October in the Hong Kong Observatory's records

The warmest October in the Hong Kong Observatory's records
(1 November 2008)

The monthly mean temperature of October 2008 recorded at the Hong Kong Observatory was 26.5 degrees, the warmest since records began in 1884. It is 0.1 degree higher than the monthly mean temperature of 26.4 degrees recorded in 1983 and 2006.

According to recent climatological records (using 1971 to 2000 as the reference period), there are on average about 6 days with minimum temperatures below 22.0 degrees in October. However, there was not a single day this October with temperature below 22.0 degrees.

From the perspective of large-scale weather situation, the main reason for the unusual warmth in Hong Kong in October this year was that the northeast monsoon was rather weak. Thus cool air failed to reach the south China coastal areas.

This record-breaking temperature reflects to some extent the long-term warming trend in Hong Kong. According to the records of the Hong Kong Observatory from 1959 to 2008, the monthly mean October temperatures of the past 50 years showed a long-term rising trend of about 0.2 degrees per decade (see Figure 1). It is also of interest to note that half of the 10 warmest Octobers occurred in the past decade (see Table 1).

Table 1. Monthly mean temperature of the 10 warmest months of October, recorded at the Hong Kong Observatory Headquarters

Figure 1. Trend of the monthly mean temperature of October recorded at the Hong Kong Observatory Headquarters in the past 50 years (1959-2008)