California's Napa Valley
Summer days can be quite warm in northern California’s inland valleys, even those that lie fairly near the coast.

Summer days can be quite warm in northern California’s inland valleys, even those that lie fairly near the coast. By evening, though, the warm, moist air is cooled by the bitterly cold Pacific Ocean, resulting in a thick bank of offshore fog. From miles out to sea, the fog begins its eastward march, covering the beaches and then the hills of the Coast Range, where it settles like misty lakes in the inland valleys.

Most people find this daily pattern of hot arid days and cool moist nights–with an almost guaranteed absence of rainfall for months on end–to be very pleasant. Wine grapes love it. In combination with local soil conditions, the fluctuating summer temperatures produce exceptional wines, a fact that the region’s initial settlers appreciated.