In spring, the axis of the Earth is tilted toward the Sun and the length of daylight rapidly increases for the relevant hemisphere. The hemisphere begins to warm significantly causing new plant growth to "spring forth," giving the season its name. Snow, if a normal part of winter, begins to melt and streams swell with runoff. Frosts, if a normal part of winter, become less severe. Many temperate climates have no snow and may have no frosts, and the air and ground temperature increase. Many flowering plants bloom this time of year, in a long succession sometimes beginning even if snow is still on the ground, continuing into early summer. In normally snowless areas "spring" may begin as early as February