Dreaming of a White Christmas? It may all be in the stars! by Professor Anne Lawrence

Recent forecasts and news stories have raised hopes of a white Christmas, even though the Met Office has pointed out that there has only been a widespread covering of snow on Christmas Day in the UK four times in the last 51 years.  They also warn that accurate forecasts of snow on a specific day can only be made 5 days in advance.  For more details see:  https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/snow/white-christmas 

Snow at Greenwich, December 2017

However, medieval and early modern meteorologists had no such problems and could predict the weather several years ahead!  The downside, of course, was that their forecasts were made on a basis which has subsequently been shown to be entirely unscientific, and accuracy was thus more by accident (and experience) than design.

Astrometerorlogical forecast for October 1590 (image copyright University of Reading Special Collections)

This year, the History Department decided to experiment and see whether medieval methods would forecast a white Christmas in 2020.  The results follow!

Medieval and early modern forecasters made their Prognostications on the basis of astrometeorology, so the first step is to calculate where the planets will be on the chosen dates, as seen from the relevant place.  In this case the relevant place is Berkshire, and the chosen period is 20th to 27th December, focusing on Christmas Day.  The locations of the planets are, of course, calculated in relation to the zodiac – and only the planets known before 1700 are used.

The Sun will start in Sagittarius (28°) and move into Capricorn (3° on Christmas Day)

The Moon will move across Pisces and Aries, and reach 6° Taurus on Christmas Day

Mercury will be close to the Sun, at 6° Capricorn on Christmas Day

Venus will be in Sagittarius (12° on Christmas Day)

Mars will be near the Moon on Christmas Day, at 24° Aries (the Moon will have moved through this position on Christmas Eve)

Jupiter and Saturn will be in very close Conjunction, in the first degree of Aquarius. 

These two powerful planets have been moving closer through 2020 and will come closest of all at the Winter solstice.  They have not been this close since the 13th century – and medieval astrologers agreed that this placing signified major events affecting large regions on Earth.  

For weather forecasters, the element linked to each planet (Earth, Fire, Air and Water) was important, as was the degree of power attributed to each planet.  The sign placings are significant as each sign was also linked to an element and to factors affecting the weather.  Finally, the relationships of the planets to one another (their aspects) also needed to be taken into account as well as their directions of movement.

Traditionally, a powerful placing for Saturn signified colder-than-usual weather, making snow perhaps more likely.  However, the conjunction with Jupiter may predict unusual or dramatic weather; and its occurrence in the Air sign of Aquarius could mean strong winds or storms.  It is also important that the pairing of Jupiter and Saturn is in a significant relationship to the Sun and Mercury, which are in the Earth sign of Capricorn – another cold location.  Mercury is fast-moving and believed to cause turbulence in the air; and the powerful, fiery planet, Mars, is in a significant aspect with Mercury and the Sun.  Mars is placed in the Fire sign of Aries, which suggests that the winds are likely to be warm.

It looks as if the medieval prognostication for Christmas 2020 would be that it will see strong, warm winds blowing over very cold ground – a combination which could produce snow-storms but is unlikely to result in a picture-perfect white Christmas!  So we can all feel very happy that this is unlikely to be correct.

Snow in February (Tres Riches Heures du Duc de Berry)

A medieval white Christmas (from the Torre Aquila in Trent

Find out more about Professor Anne Lawrence Mathers and her research at the University of Reading here

You can also find out much more in her book Medieval Meteorology

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