Children collect sweet things, teenagers watch horror films, adults dress up to frighten each other and many pumpkins become backlit scary faces. This is the tradition of Halloween on October 31 in much of the world.

It is widely believed that many Halloween traditions originated from ancient Celtic harvest festivals, particularly the Gaelic festival Samhain. Such festivals may have had pagan roots; Samhain itself was Christianised as Halloween by the early Christian Church.

This festival is not recognised outside the western world, but the date is climatologically significant in that it ends the three-month climatological autumn. Figures will now be confirmed and compared, by climatological statisticians, with autumn seasons from previous years.

The end of October often sees a change of weather too.

The Indian monsoon withdraws to the tip of India and Sri Lanka and the second cyclone season begins in the Arabian Sea and the Bay of Bengal. The Australian cyclone season officially begins.

Both Australia and South Africa have seen particularly stormy spring seasons and are settling now into summer.

China has entered its winter season with the northeast monsoon now prevalent. In the United States, the last few days of October brought some proper snow to the northern states.

Northern Europe has been battered by a windstorm followed by a big drop in temperature. The system responsible is still covering Belarus in snow. Western Europe, and in particular Iberia, is yet to realise the change of season.