The Weather of July 2007

    Under the prolonged dominance of the sub-tropical ridge of high pressure, July 2007 was much drier and warmer than usual. The monthly rainfall of 76.9 millimetres, less than one fourth of the normal figure of 323.5 millimetres, was the lowest on record for July. With abundant sunshine and meager rainfall, the monthly mean temperature mounted to 29.6 degrees, the second highest for July. The accumulated rainfall since the beginning of the year was 1044.9 millimetres, about 21 percent below the normal figure of 1316.0 millimetres for the same period.

    Under the influence of a trough of low pressure over the south China coast, it was mainly cloudy with a few showers in the first day of the month. The trough of low pressure dissipated the next day. There were sunny periods and a few showers between 3 July and 6 July.

    With a ridge of high pressure dominating over the southern China, it was fine, clear and very hot on 7 July. Apart from a few isolated showers, the fine and clear weather persisted in the following nine days.

    A fresh southwesterly airstreams brought some showers to the territory on 17 July and the ensuing two days.

    It was sunny on 20 July when the southwesterlies moderated. The weather stayed generally fine and clear for the rest of the month under the influence of a ridge of high pressure over southeastern China. With sunshine aplenty, the temperature rose to 34.8 degrees on 28 July, the highest in the month.

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

    Details of issuance and cancellation of various warnings/signals in the month are summarized in Tables 1.1 to 1.2.  Monthly meteorological figures and departures from normal for July are tabulated in Table 2.