Beijing lies in the continental monsoon region in the warm
temperature zone and its climate represents as hot and rainy in
summer and cold and dry in winter.
The four seasons in Beijing are distinct. It is dry, windy and
sandy in spring and hot and rainy in summer. Autumn is the best
season in a year when the sky is blue; the air is crisp, mild and
humid. However, winter is cold and dry with little snow. The
average temperature throughout a year is 11.7. The average
temperatures of the hottest month, July and the coldest month
January range from 27 and -4.6. The shorter seasons, spring
(usually from February to April) and autumn (usually from August to
October) are better seasons for visiting Beijing when it is sunny
and warm with few tourists crowding in the attractions.
If you come to Beijing in spring, you could wear a thin sweater,
a pair of sweat pants, and a coat. But sometimes it may be a good
idea to bring a warm cap because it is windy and sandy during this
period though it is not cold. In summer the temperature could reach
as high as 30. When you go out, you could take an umbrella along
with you if it doesn't bother you much, because a downpour may come
unexpectedly at evenings from July to August. Autumn is the most
beautiful season, but after October you may feel the constant
changes of the weather and you may encounter light rains at any
moment. So it is better to bring some heavy clothes with you. In
winter, you need a heavy woolen sweater, and a long wind coat or a
down jacket. Generally there will be two or three heavy snowfalls
each winter, so it is always wise for you to have anti-skidding
shoes with you when you come. Lastly, don't wear light-color
clothes in winter.
(Source: BOCOG)