Warmest January on record
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     With no significant cold surge affecting the coastal areas of Guangdong, January 2017 was the warmest January on record in Hong Kong with record-breaking monthly mean temperature of 18.5 degrees and monthly mean minimum temperature of 17.0 degrees, 2.2 degrees and 2.5 degrees above their respective normals. The month was drier than usual with total rainfall of only 7.8 millimetres, less than one-third of the normal of 24.7 millimetres.    
 
     Under the influence of an easterly maritime airstream, the weather in Hong Kong was mild with a mixture of sunshine and clouds for the first five days of the month. The weather turned generally fine on January 6 with abundant sunshine over the next two days. Temperatures at the Hong Kong Observatory rose to a maximum of 25.5 degrees on January 8, the highest of the month. The arrival of a replenishment of the northeast monsoon that night brought cloudier and slightly cooler weather in the next two days.
 
     With a strengthening easterly airstream and cloud bands associated with a low pressure area over the South China Sea moving towards the coastal areas of Guangdong, a spell of cloudy and misty weather set in over the territory on January 11. As replenishments of the northeast monsoon reached the south China coast, local weather turned overcast and progressively cooler with rain patches on January 12 to 16. With the northeast monsoon moderating gradually, the weather became warmer. The lingering cloud bands started to dissipate and gave way to mainly fine weather on January 19.
 
     Following the arrival of a significant replenishment of the northeast monsoon, continental northerly winds brought dry and cooler weather to Hong Kong on January 20 to 22, with relative humidity falling below 40 per cent during the day over the weekend. Under clear skies, temperatures at the Hong Kong Observatory fell to a minimum of 13.6 degrees on the morning of January 22, the lowest of the month. Despite a strengthening easterly airstream on January 24, fine weather persisted from January 23 to 27. Affected by a moist easterly airstream, local weather became cloudy on January 28 with rain patches and poor visibility in some areas over the Chinese New Year holiday period. The weather turned appreciably cooler by the end of the month as a fresh to strong easterly airstream brought a replenishment of the northeast monsoon to the south China coastal areas on the night of January 30.
 
     One tropical cyclone occurred over the South China Sea and the western North Pacific in the month.
 
     Details of the issuance and cancellation of various warnings/signals in the month are summarised in Table 1. Monthly meteorological figures and departures from normal for January are tabulated in Table 2.

Ends/Thursday, February 2, 2017
Issued at HKT 12:00

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