In the summer, when the land heats faster than the ocean, low pressure forms over Asia and warm, moist south to southeasterly winds bring heavy, thundery rain, yielding annual rainfall ranging from 400 mm (16 in), or less in the west, to over 1,150 mm (45 in) in the Changbai Mountains.[36] Temperatures in the summer are very warm to hot, with July average maxima ranging from 31 °C (88 °F) in the south to 24 °C (75 °F) in the extreme north.[37] Except in the far north near the Amur River, high humidity causes major discomfort at this time of year.[citation needed]