North America

North America stretches from roughly 800 km of the North Pole to within the same distance of the Equator, packing nearly every Köppen climate type into one continent: polar tundra and subarctic forest in the north, humid continental and humid subtropical across the eastern half, a narrow Mediterranean strip on coastal California, vast semi-arid plains and true desert in the interior southwest, and tropical rainforest, monsoon, and savanna across Central America and the Caribbean.

The Rocky Mountains, Sierra Nevada, and Cascades dominate the precipitation map: westerly winds drop heavy rain and snow on their windward slopes, then leave a deep rain shadow over the Great Basin and the Sonoran, Mojave, and Chihuahuan deserts, where annual totals fall below 250 mm. The continental average is roughly 760 mm.

Distinctive regional regimes layer on top — Atlantic hurricane season along the Gulf and southeast coasts, the North American Monsoon over northwest Mexico and the southwestern United States, Tornado Alley across the central plains, and winter polar-vortex intrusions deep into the interior.

Our archive covers 3 North American cities with daily ERA5 reanalysis data going back to 1940. The warmest July averages occur in Los Angeles, around 30°C, while New York City records the coldest January nights near −3.7°C. Comparing the last decade against the 1940–1970 baseline, mean temperatures across these cities have risen by about 1.9°C, with the strongest warming in the high latitudes.