Tokyo is classified as lying in the humid subtropical climate zone and has four distinct seasons. Summers are usually hot and humid with a temperature range of about 20-30°C (68-86°F), though it can sometimes climb into the high thirties. Winters are usually mild, with temperatures generally ranging from 0-10°C (32-50°F), though occasional cold spells can send temperatures plummeting below zero at night. Snow is rare, but on those rare occasions (once every few years) when Tokyo is hit by a snowstorm, much of the train network grinds to a halt. The famous cherry blossoms bloom in March-April and parks, most famously [wiki=f9e2255868a544be866551034bb821df]Ueno[/wiki], fill up with blue tarps and sozzled salarymen.