From autumn to spring in December 1806

When I was writing up my winter forecast I came across an analogue that was very similar to what happened during the period November 10th to December 31st.

mean 1806 v 2015

The period November 10th – December 31st in 1806 and 2015 show some striking similarities. It is also notable that mean during 2015 was 3C higher than 1806. Is this a question of synoptics or a warming world?

 

The results showed a close similarity between the two periods, November 10th – December 31st, though the mean in 2015 was some 3C warmer than 1806. Is this a question of synoptics or is this area now 3C warmer than it was just over 200 years ago?

Rainfall was also remarkably similar: 87.7mm fell from 10/10 – 31/12, just over 5mm more than 1806.

rain 1806 v 2015

The period November 10th – December 31st in 1806 and 2015 show some striking similarities. It is also notable that mean during 2015 was 3C higher than 1806. Is this a question of synoptics or a warming world?

Luke Howard, in his first volume of The Climate of London, describes a very warm December that followed on from a warm November that fooled flora and fauna into thinking spring had begun early.

Howard’s statistics are very high: a November mean of 9.5C while December was 7.2C. CET that November was 2.3C above average while December was 3.3C above average. Considering the England Wales Precipitation series a slightly wetter than average November was followed by a very wet December – over 250% the monthly average.

“The catkins of the filberts expanded prematurely. On December 25th a hedge sparrow’s nest was taken at Doveridge, Derbyshire, with four eggs and near Warwick a green linnet’s with two eggs. It is worthy of remark that the heat was the same on December 24th as on June 24th last – on both those days the thermometer being nearly 60F.”

Howard goes on to describe how the south-west wind had “reigned for weeks” – for most of November and December before finally giving way at the turn of the year.

“The south west wind which had so long reigned yielded just at the close of the year to the north and west . Some frost ensued which, however, had not the characters of permanence being neither ushered in by driven snows nor accompanied with a dry and serene atmosphere.”

The River Lea close to where Luke Howard's laboratory stood by wanstead_meteo

The period November 10th – December 31st in 1806 and 2015 show some striking similarities. It is also notable that mean during 2015 was 3C higher than 1806. Is this a question of synoptics or a warming world?

His description is not dissimilar from what is known as a “three-day toppler” cold spell where a dominant European high briefly gives way to cold air from the north-west or north, bringing often heavy snow to Scotland and the north but just a few cooler days in the south, before the cold feed is cut off as the high re-establishes itself.

Howard also describes how the warmth affected plants.

“The effects of the late high winter temperature on vegetation must have been obvious to everyone who has seen the country. To the very close of the year the grass continued to grow, the daisies to enamel the turf and many of the inmates of our gardens native and exotic to thrive and blossom. Even hyacinth bulbs left in the open beds shot up and flowered. Ten years ago winter came on six weeks earlier and with considerable severity.”

Words that echo what’s going on this month, particularly in the south-west where I’ve heard reports of roses still in bloom and affected by greenfly whiles daffodils look like they will be out in a couple of days.

January and February 1807 were, by the standards of that time, roughly average.

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13 responses to “From autumn to spring in December 1806

  1. December 1806 was a particularly notable month in a period that for mild winters was a literal blank. In fact, only three winters from 1760 to 1821 could be called “mild” by twentieth-century standards, and two of those (1778/1779 and 1789/1790) were anticyclonic with warm airflows. Between 1796/1797 and 1815/1816, no winter had a CET above 4.43°C. It was the freakish year of 1821/1822 (but for the appalling transport and energy policies of Canberra and Melbourne, that would still be the hottest CET fiscal year no doubt) before another winter above 4.75°C.

    It is true that between January 1797 and December 1813, there were no exceptionally cold months – indeed no month had CET under 1.0°C in the 1800s, despite that decade being the driest since the EWP series began. However, between 1807 and 1816 no January had a CET above 2.8°C, and of course January 1814 is probably the coldest month over the UK as a whole in the past three centuries. The mean January CET from 1807 to 1816 was in fact 1.5°C, and since March 1895 only 25 months have been colder than that.

    Yet, December 1806 averaged 6.8°C, which was the warmest since the then-record-hot year of 1733 and was not to be topped again until a non-continuous cluster of very warm Decembers between 1827 and 1857. Between 1797 and 1821, February 1815 and February 1817 were the only other winter month to average over 6.0°C, and only January 1804 and Februaries 1809, 1812 and 1813 and 1817 and February 1813 otherwise averaged over 5.0°C.

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  2. In the early 80’s we had two exceptionally mild winters and a couple of exceptionally cold. I remember vividly eating Christmas lunch with the patio doors open as we were so hot with the sun streaming in, our kids were outside playing with their new toys and as a bonus we had very low energy costs that winter. Another year the village was literally snowed in, I took loads of photos as it was so beautiful and unusual. This is, and always has been, the joy of living in the UK.

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    • Yes, totally unpredictable out past a couple of days. My daughter was on the trampoline earlier today for first time in weeks – as I cut the grass. Not many times I’ll be able to say that on December 19th

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  3. Reblogged this on naturestimeline and commented:
    December 2015 is most definitely an odd one. With its weather statistics and Natural World tales it becoming one for the history books. Although, it is worth noting that we have been here before, as this example from 1806 shows. Of course, those current mean Temperatures of 5.4c above average could and perhaps should still be viewed as rather concerning.

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  4. Hi,

    As the madness continues with my weather station showing a mean Air Temperature of some 10.4c in Berkshire, I’ve decided to reblog this post on naturestimeline, I trust you won’t mind.

    Best Wishes

    Tony Powell and naturestimeline

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  5. Current weather anomalies seem to be coming less anomalous and more the norm. It’s profoundly worrying. Everyone I speak to about it is noticing it and expressing concern

    BTW How are average temperatures calculated?

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    • The pattern seems to be going back to what the climate was like 200 years ago – with all extremes of weather possible.

      For my averages, going back to 1797, I use a combination of data from Greenwich and my own data that I have collected since 1988

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  6. Pingback: From autumn to spring in December 1806 | Old School Garden·

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