There are different views on when the season starts and finishes, for example the Oxford English Dictionary says that spring is in the Northern hemisphere from

March to May and in the S. hemisphere from September to November. Whilst the Cambridge Advanced Learner's Dictionary considers that spring lasts "from March to June north of the equator, and from September to December south of the equator".

As in summer, the axis of the Earth is tilted toward the Sun, and the length of daylight hours rapidly increases as latitude increases. The hemisphere begins to warm significantly, causing new plant growth to "spring forth", giving the season its name . Snow begins to melt, rivers and streams swell with runoff and spring rains. Most flowering plants bloom this time of year, in a long succession beginning even when snow is still on the ground, and continuing into early summer. In normally snow-less areas, "spring" may begin as early as February during warmer years, with subtropical areas having very subtle differences, and tropical ones none at all.

Sub-arctic areas may not see "spring" at all until May or even June, or December in the outer Antarctic.