As it relates to wine:

Sunshine is the first, and most important, requirement for viticulture. Sunlight powers photosynthesis, which allows the vines to grow, producing leaves and grape berries as a result. Without adequate rays and the heat that comes with them, vines will die. In general, grapes thrive between the 30th and 50th latitudes, where temperatures are warm enough for plant processes to occur. Outside of this belt, which encompasses every famous wine region in the world, winters can be too severe for vines to survive, or summers can be too hot or aren’t hot enough to support adequate ripening. A vineyard or region’s exact spot within the grape belt reflects the length of its ripening season. For example, vineyards in the northern reaches of Washington state benefit from long sunny days with cool temperatures, allowing grapes to ripen very slowly. Vineyards stretched across sun-baked swaths of Southern Spain and Portugal have shorter, hotter days where ripening happens rapidly.

In cooler areas at the edge of the grape belt, such as New York’s Finger Lakes or Germany’s chilly Mosel Valley, south-facing hillsides that maximize sun exposure are critical to grape ripening. Locales with similar temperatures, but without good exposure–like Connecticut, Poland or North Dakota–can’t make fine wines for this reason.