The climate of the islands is mild and pleasant, with no major fluctuations in temperature thanks to the protection of the Alps and the heat storage in Lake Maggiore. This allows the planting of Mediterranean and subtropical plants. The temperature rarely drops below 0 ° C. There are around 1700 species in the botanical garden on the Big Island The planted species come from the regions with a Mediterranean climate (Mediterranean area, Chile, South Africa, South and West Australia, California) and from the zones with a humid tropical climate (especially Asia, but also North and South America and Oceania).