North America's Average Rainfall: 710 mm, But Highly Variable

The continental average annual precipitation is approximately 710 millimeters (28 inches). However, this figure masks extreme diversity:

• Pacific Northwest / SE Alaska: 2,500–4,000+ mm (temperate rainforests).
• Gulf Coast / Florida: 1,300–1,600 mm (thunderstorms, hurricanes).
• Eastern Deciduous Forest: 1,000–1,300 mm.
• Great Plains: Gradient from 800 mm (east) to 300 mm (west rain shadow).
• Southwest Deserts (Mojave, Sonoran): < 250 mm.
• Arctic/Subarctic: 250–500 mm (low evaporation).

Drivers: latitude, prevailing westerlies, orographic lift (Rockies, Cascades, Appalachians), proximity to moisture sources (Pacific, Gulf, Atlantic), and rain shadows.