Bolivia's climate varies dramatically due to its diverse topography, from tropical lowlands to high Andean plateaus. Covering over 1 million km², the country features tropical humid climates in the eastern plains, dry and polar conditions in the western Altiplano, and transitional zones in between. Temperatures range widely with elevation: hot and humid in the lowlands averaging 30°C, cooler subtropical highlands around 15-20°C daytime dropping near freezing at night, and arid cold in the highlands. Rainfall spans from very low in the dry Altiplano to very high in rainforest areas. Expats should prepare for altitude effects in the west, intense solar radiation, and seasonal flooding in the east. Köppen classifications include tropical (A), dry (B), temperate (C), and polar (E) types.