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GEOGRAPHY
fogs occur from time to time in early spring-during breaks in the monsoon--when warm south-easterly winds may temporarily displace the cool north-easterlies.
From mid-April until September the south-west monsoon prevails, but it is not as persistent as the winter monsoon. During this part of the year the weather is almost continuously hot and humid, and is often cloudy and showery with occasional thunder- storms. Summer is the rainy season.
The annual rainfall, as measured at the Royal Observatory, has varied between 46 inches and 120 inches, but the normal value is 85 inches. On average the five dry months from November to March yield only 9 inches as compared with 76 inches spread over the other seven months.
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There is also considerable variation in rainfall over different parts of the Colony. The wettest areas are the mountain regions, particularly around Tai Mo Shan and on Lantau Island. Least rainfall occurs on the offshore islands which usually receive little more than half the rainfall of the wettest areas.
The mean daily temperature ranges from about 58°F in February to over 82°F in July and the average for the year is 72°F. During the hottest month, July, the mean maximum temperature is 86.9°F but the summer temperature often exceeds 90°F. February is the coldest month with a mean minimum temperature of 55.6°F but the temperature can be expected to fall to 45°F in most_years. Temperatures above 95°F or below 40°F are rarely recorded at the Observatory although greater extremes occur in the New Territories. Ice occasionally forms on high ground. Afternoon temperatures are usually 8°F to 9°F hotter than the coldest part of the night.
The mean relative humidity exceeds 80 per cent from mid- February until early September. November is the least humid month with 69 per cent relative humidity but the lowest reading of 10 per cent was recorded in January. The average daily duration of bright sunshine ranges from 3 hours in March to over 7 hours in mid-July and in late October.
Gales caused by tropical cyclones may be expected in any of the months from May to November, but they are most likely from July to September. The passage of these cyclones several