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 Northwest winds are the prevailing winds of the greater part of the United States. They are also the clearing winds for most of the cyclonic storms that sweep the country; they constitute practically all the cold-wave winds.

Southwest winds are the prevailing winds during the summer months in the eastern part of the United States. With a falling barometer, they bring rain.

Northeast winds are storm-winds; almost always they are cold and raw.

Southeast winds are rain winds along the entire coast and much of the interior of the United States, for the greater part of the year. The time varies from twelve to eighteen hours in winter and from eighteen to thirty-six hours in summer.

Barometer and Wind Indications.—When pressure and wind-direction are both considered and interpreted according to their mutual relations, local forecasts can be made with a much greater degree of certainty. During the colder months, throughout the United States, the western highlands excepted, precipitation begins with falling pressure. In the summer months, and in the western highlands it is apt to begin with the rising barometer. The following indications have been compiled for the Weather Bureau by Garriott.