Spring 2025: When does spring start, when do the clocks go forward and why?

As winter fades, daylight is increasing rapidly - by about four minutes each day.

The sun is also beginning to carry a hint of warmth, making you wonder if spring is just around the corner.

However, opinions vary on when winter officially ends.

Thus, there are two possible start dates for spring, depending on whether you follow the meteorological or astronomical definition.

Weather forecasters consider spring to begin on March 1.

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In meteorology, seasons are divided into three-month periods for consistency in weather and climate analysis. Spring consists of March, April, and May, ending on May 31, before summer takes over in June.

This fixed timeframe makes it easier to compare weather patterns year after year, unlike astronomical spring, which shifts slightly each year based on Earth's orbit around the Sun.

Perhaps the more common idea of when spring begins is astronomical spring. This date varies slightly each year, but in 2025, it will begin on March 20.

Astronomical spring is marked by the spring equinox, which is determined by Earth's tilt as it orbits the Sun.

On the equinox, the Sun crosses the equator, making day and night nearly equal in length. The word "equinox" comes from Latin, where equi means "equal" and nox means "night." After the equinox, daylight hours continue to increase.

Astronomically, spring ends on June 21, at the summer solstice.

Another way to mark the start of spring is through phenology—the study of how plants and animals respond to seasonal changes in weather and climate.

For nature observers, phenological spring doesn’t have a fixed date, as it varies depending on species and local weather conditions.

For example, frogspawn may appear as early as late February, while bluebells tend to bloom in early April.

However, climate change is shifting these natural events. Data from a citizen science project with the Woodland Trust shows that since 2000, species like frogspawn and bluebells have been appearing earlier than before.

When and why will the clocks go forward?

If you're familiar with the phrase, the clocks will "spring forward" by an hour. Thus, as we transition toward longer days, clocks will move from Greenwich Mean Time (GMT) to British Summer Time (BST) on March 30.

For most of us, this means we lose an hour of the day, but in return, our evenings become significantly lighter.

Clocks go forward in the summer for daylight saving - an idea first introduced in 1907 by William Willett, a British builder who noticed people were sleeping through the daylight on summer mornings.

He proposed shifting the clocks forward to help everyone make better use of the daylight, and thus, the Summer Time Act was passed by Parliament in 1916.