Spring is the season which marks the transition from Winter, the coolest season to Summer, the warmest season. During the Winter, either the Northern Hemisphere or Southern Hemisphere is exposed to less direct sunlight. In Spring, the given hemisphere is gradually exposed to more and more of this direct sunlight, until it is exposed to a large amount in Summer. Thus, throughout Spring the temperature generally becomes warmer and warmer. The season typically begins in March in the Northern Hemisphere and September in the Southern Hemisphere. It then occurs until May or November in the Northern Hemisphere and Southern Hemisphere respectively. The effects of Spring are felt in the more temperate places of each hemisphere, whilst places closer to the equator experience very little or none of the changes.
The onset of Spring drastically occurs in the last meteorological month of Winter (February in the Northern Hemisphere, August in the Southern Hemisphere), as it is then that the change in the Earth's tilt is marked. However, due to seasonal lag, the meteorological Spring does not begin until a month later as the ground and oceans are cool after being heated very little throughout the Winter. Thus, cool temperatures may be common as late as March and April in the Northern Hemisphere or September and October in the Southern Hemisphere, due to the ground and oceans being at their coolest, even though a large amount of direct sunlight is being received. Meanwhile, snowfall is fairly likely to occur near the beginning of the season in temperate regions, although the last frosts after the Winter are likely to occur after that.