This infographic, commissioned by BBC Focus Magazine, illustrates when spring begins and the possible answers the data may show. 

Springtime is shifting – its onset is arriving earlier than it used to, and there are a number of factors that illustrate this change. Using the visual metaphor of a sundial, reminiscent also of a sunrise or a blossoming flower, the infographic overlays multiple datasets to show a pattern in the shift.

The highlighted evidence of these changes includes consistent increases in UK monthly daytime temperatures, earlier emergence of springtime events tracked Woodland Trust’s Nature’s Calendar Survey,  including the February (no longer March) singing of Song Thrushes, the flowering of Snowdrops in January, and changes in leafing & flowering schedules of Hawthorns and horse chestnuts.