Maritime airstreams around Hong Kong make for warmer, drier March

PUBLISHED : Friday, 03 April, 2015, 7:00am
UPDATED : Wednesday, 15 April, 2015, 2:00pm

The city enjoyed a warmer and drier March than usual, mainly due to the dominance of maritime airstreams during the latter half of the month, statistics from the Hong Kong Observatory showed on Thursday.

The monthly mean temperature recorded was 19.9 degrees Celsius, 0.8 degrees higher than the normal, which is an average of figures taken from 1981 to 2010.

The Observatory also said the total rainfall for March was just 28.4 millimetres – about 35 per cent of the expected figure of 82.2 millimetres.

The 102.1 millimetres of accumulated rainfall that fell since January 1 was also about 37 per cent below the expected figure of 161.3 millimetres for the same period.

The month started under the influence of a cold front over southern China that moved across the coastal areas of Guangdong on March 1.

The strengthening of an easterly airstream the next day also added to the cooler weather.

The mercury dropped further on March 4 and 5 when another replenishment of the northeast monsoon brought windy and cooler conditions.

The weather remained cloudy with light rain and mist patches until March 8.

On March 10, easterly winds strengthened again as another replenishment of the northeast monsoon reached the coast of Guangdong, pulling the mercury down further with light rain patches over the city for the following few days.

Temperatures at the Observatory headquarters in Tsim Sha Tsui fell to a minimum of 14.8 degrees on March 12, the lowest for the month.

A twist was seen on March 14 and 15 as the northeast monsoon subsided and was gradually replaced by a warmer maritime airstream. The temperature and humidity rose with the onset of foggy and cloudy conditions.

Fine weather prevailed for the following few days and temperatures at the Observatory headquarters climbed to a maximum of 28.3 degrees on March 20 – the highest recorded for the month.

With easterly winds strengthening and the northeast monsoon returning to the Guangdong coast, the weather turned cooler and generally cloudy and windy with light rain patches from March 22 to 26.

After March 27, sunny intervals appeared in the afternoon as warm maritime air set in over Guangdong, when clouds thinned out during the day and sunny periods increased towards the end of the month.

In a forecasting the weather for the Easter and Ching Ming holidays, scientific officer Li Tsz-ka said it would remain warm and fine over the weekend until Monday, with maximum temperatures reaching 28 degrees Celsius.

“But a strong north-east monsoon reach southern China on Tuesday, and the mercury will drop to as low as 19 degrees on Thursday with rainy and cloudy conditions,” Li said.

Li said typhoon Maysak east of the Philippines had been weakening and was expected to further weaken after making landfall. He added that the low water temperatures in South China Sea would not be beneficial to its development.