Beijing has a continental monsoon climate with clear-cut seasons. Spring is dry and windy, due to the Siberian air masses that move southward across the Mongolian Plateau.  The summer months, June to August, are hot and humid with about 40% of the annual precipitation.  Autumn offers the best weather, with generous sunshine.  Winter usually begins towards the end of October.  The city is severely affected by freezing winds from Siberia.  In November, the average temperature in Beijing is 4.1 degrees Celsius and the mean rainfall is 6.6mm.  January is the coldest month