Spring is one of the four conventional temperate seasons, following winter and preceding summer. There are various technical definitions of spring, but local usage of the term varies according to local climate, cultures and customs. When it is spring in the Northern Hemisphere, it will be autumn in the Southern Hemisphere. At the spring equinox, days are approximately 12 hours long with day length increasing as the season progresses. Spring and “springtime” refer to the season, and also to ideas of rebirth, rejuvenation, renewal, resurrection and regrowth. Subtropical and tropical areas have climates better described in terms of other seasons, e.g. dry or wet, monsoonal or cyclonic. Often, cultures have locally defined names for seasons which have little equivalence to the terms originating in Europe.
Meteorologists generally define four seasons in many climatic areas: spring, summer, autumn (fall) and winter. These are demarcated by the values of their average temperatures on a monthly basis, with each season lasting three months. The three warmest months are by definition summer, the three coldest months are winter and the intervening gaps are spring and autumn. Spring, when defined in this manner, can start on different dates in different regions.
In terms of complete months, in most north temperate zone locations, spring months are March, April and May, although differences exist from country to country. (Summer is June, July, August; autumn is September, October, November; winter is December, January, February). Most south temperate zone locations have opposing seasons with spring in September, October and November. Swedish meteorologists define the beginning of spring as the first occasion on which the average daytime temperature exceeds zero degrees Celsius for seven consecutive days, thus the date varies with latitude and elevation. In Australia and New Zealand, spring conventionally begins on 1 September and ends 30 November.
The beginning of spring is not always determined by fixed calendar dates. The phenological or ecological definition of spring relates to biological indicators; the blossoming of a range of plant species, and the activities of animals, or the special smell of soil that has reached the temperature for micro flora to flourish. It, therefore, varies according to the climate and according to the specific weather of a particular year. Most ecologists divide the year into six seasons that have no fixed dates. In addition to spring, ecological reckoning identifies an earlier separate prevernal (early or pre-spring) season between the hibernal (winter) and vernal (spring) seasons. This is a time when only the hardiest flowers like the crocus are in bloom, sometimes while there is still some snowcover on the ground.
