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  • The Weather of July 2016

  • 1 August 2016

    With long spells of sunny skies under the dominance of the subtropical ridge, the weather was unusually hot in July 2016. The monthly mean temperature of 29.8 degrees was 1.0 degree higher than the normal figure of 28.8 degrees, equalling the previous highest record set in 2014. The month was much drier than usual with only 175.9 millimetres of rainfall, less than half of the July normal of 376.5 millimetres. The accumulated rainfall of 1408.7 millimetres for the first seven months was about 4 percent below the normal figure of 1473.3 millimetres for the same period.

    Under the influence of an active southerly airstream, the weather in Hong Kong was hot with a mixture of sunshine, showers and thunderstorms on the first five days of the month. The setting in of an easterly airstream along the coastal areas of Guangdong gave rise to a relatively cool day on 6 July as rainbands from the northern part of the South China Sea brought heavy showers and squally thunderstorms to Hong Kong. More than 30 millimetres of rainfall fell over the territory and the lowest temperature of the month, 24.7 degrees, was recorded at the Hong Kong Observatory in rain that morning.

    Over the western North Pacific, Super Typhoon Nepartak headed towards Taiwan on 7 July and made landfall at Fujian two days later. Affected by the subsiding air outside the circulation of Nepartak, local weather was sunny and very hot on 7 - 9 July. The oppressive heat was most keenly felt on 9 July with temperature at the Hong Kong Observatory soaring to a maximum of 35.6 degrees, the highest of the month and the second highest for July on record. Intense convection developed over inland Guangdong on the afternoon of 9 July and moved towards Hong Kong in the evening, bringing squally thunderstorms with incessant lightning and thunder that lasted throughout the night. Local weather remained mostly cloudy and unsettled with occasional heavy showers and thunderstorms over the next five days.

    With an upper-air anticyclone becoming established over southeastern China and the northern part of the South China Sea, a spell of generally fine weather with rather hot conditions set in on 15 July and persisted for more than two weeks. Despite a showery interlude on 19 - 20 July, there were still long hours of sunshine and temperature at the Hong Kong Observatory once again reached 35 degrees on 25 July as a tropical depression brewed over the central part of the South China Sea. It intensified into a tropical storm named Mirinae the next morning and its outer rainbands brought squally showers and thunderstorms to Hong Kong during the day. With Mirinae moving away towards Hainan Island and northern Vietnam, fine and very hot weather prevailed in Hong Kong towards the end of the month. The high temperature on the afternoon of 30 July also triggered intense thunderstorm development over the New Territories. Hail was reported at Tai Po during the passage of the thunderstorms.

Thunderstorms over Ting Kau Bridge on the night of 9 July 2016
Thunderstorms over Ting Kau Bridge on the night of 9 July 2016. (courtesy of Mr Jeffrey Poon)


Lightning strike as seen from Sai Wan Ho on the night of 9 July 2016
Lightning strike as seen from Sai Wan Ho on the night of 9 July 2016.
(courtesy of Huey Pang@Astrolink)


Hail found at Tai Po on the afternoon of 30 July 2016
Hail found at Tai Po on the afternoon of 30 July 2016 (courtesy of Matilda Au).

    Four tropical cyclones occurred over the South China Sea and the western North Pacific in the month.

    Details of issuance and cancellation of various warnings/signals in the month are summarized in Tables 1.1 to 1.4.  Monthly meteorological figures and departures from normal for July are tabulated in Table 2.
 

Warnings and Signals issued in July 2016

Table 1.1   Tropical Cyclone Warning Signals
Name of
Tropical Cyclone
Signal
Number
Beginning Time Ending Time
Day/Month HKT Day/Month HKT
MIRINAE 1 26 / 7 0840 26 / 7 2320
NIDA 1 31 / 7 2210 1 / 8 1140


Table 1.2   Rainstorm Warning Signals
Colour Beginning Time Ending Time
Day/Month HKT Day/Month HKT
Amber 6 / 7 0835 6 / 7 1050
Amber 9 / 7 2155 9 / 7 2310
Amber 13 / 7 0735 13 / 7 0915


Table 1.3   Thunderstorm Warning
Beginning Time Ending Time
Day/Month HKT Day/Month HKT
1 / 7 0100 1 / 7 0300
1 / 7 0805 1 / 7 0900
2 / 7 0605 2 / 7 0715
2 / 7 0930 2 / 7 1005
2 / 7 1100 2 / 7 1330
2 / 7 1550 2 / 7 1800
2 / 7 2115 2 / 7 2215
3 / 7 1215 3 / 7 1515
4 / 7 0832 4 / 7 1045
4 / 7 1710 4 / 7 1815
5 / 7 0425 5 / 7 0600
5 / 7 1030 5 / 7 1730
6 / 7 0124 6 / 7 0230
6 / 7 0440 6 / 7 1330
7 / 7 0240 7 / 7 0330
8 / 7 0245 8 / 7 0345
9 / 7 1845 10 / 7 0645
11 / 7 0400 11 / 7 1030
11 / 7 1255 11 / 7 1430
11 / 7 1800 11 / 7 1935
13 / 7 0605 13 / 7 1000
13 / 7 1455 13 / 7 1800
14 / 7 0445 14 / 7 0730
14 / 7 0905 14 / 7 1330
19 / 7 0520 19 / 7 0600
19 / 7 1410 19 / 7 1515
19 / 7 2340 20 / 7 0315
26 / 7 0630 26 / 7 1530
26 / 7 1740 26 / 7 1845
26 / 7 1945 26 / 7 2230
27 / 7 0205 27 / 7 0315
30 / 7 1240 30 / 7 1630
31 / 7 2230 31 / 7 2355


Table 1.4   Very Hot Weather Warning
Beginning Time Ending Time
Day/Month HKT Day/Month HKT
1 / 7 1250 1 / 7 1745
4 / 7 1335 4 / 7 1715
7 / 7 0645 10 / 7 1615
15 / 7 0730 18 / 7 1740
20 / 7 1115 25 / 7 2100
27 / 7 1145 1 / 8 1800


Table 2   Figures and Departures from Normal - July 2016
Meteorological Element Figure of the Month Departure from Normal*
Mean Daily Maximum Air Temperature 32.6 degrees C 1.2 degrees above normal
Mean Air Temperature 29.8 degrees C 1.0 degree above normal
Mean Daily Minimum Air Temperature 27.4 degrees C 0.6 degree above normal
Mean Dew Point Temperature 25.7 degrees C 0.6 degree above normal
Mean Relative Humidity 79 % 2 % below normal
Mean Cloud Amount 63 % 6 % below normal
Total Rainfall 175.9 mm 200.6 mm below normal
Number of hours of Reduced VisibilityΔ 2 hours 13.4 hours below normal§
Total Bright Sunshine Duration 218.2 hours 6.2 hours above normal
Mean Daily Global Solar Radiation 19.50 Megajoule / square metre 2.33 Megajoule above normal
Total Evaporation 150.4 mm 4.2 mm above normal


  Remarks : All measurements were made at the Hong Kong Observatory except sunshine, solar radiation and evaporation which were recorded at King's Park Meteorological Station and visibility which was observed at the Hong Kong International Airport.

  Δ

The visibility readings at the Hong Kong International Airport are based on hourly observations by professional meteorological observers in 2004 and before, and average readings over the 10-minute period before the clock hour of the visibility meter near the middle of the south runway from 2005 onwards. The change of the data source in 2005 is an improvement of the visibility assessment using instrumented observations following the international trend.
Before 10 October 2007, the number of hours of reduced visibility at the Hong Kong International Airport in 2005 and thereafter displayed in this web page was based on hourly visibility observations by professional meteorological observers. Since 10 October 2007, the data have been revised using the average visibility readings over the 10-minute period before the clock hour, as recorded by the visibility meter near the middle of the south runway.


  *   Departure from 1981 - 2010 climatological normal, except for number of hours of reduced visibility

  §   Departure from mean value between 1997 and 2015

daily values of selected meteorological elements for HK for July 2016

The percentile map of mean temperature of July 2016

  Remarks : Extremely high: above 95th percentile
Above normal: between 75th and 95th percentile
Normal: between 25th and 75th percentile
Below normal: between 5th and 25th percentile
Extremely low: below 5th percentile
Percentile and 5-day running average values are
computed based on the data from 1981 to 2010