Spring: Nature’s Season of Confusion, by Patrick Nobbs
‘As the days grow longer, the cold grows stronger’. At first glance this piece of medieval weather lore appears rather odd, but in reality it shows just how in touch our ancestors were with nature. Spring often brings frost and snow, which is especially notable after a mild winter. But spring is a contradictory season, and it can also bring extraordinary warmth. In some years, it has provided the best weather of the entire year! All of these phenomena have happened in the last five years alone, but the further we go back in history, the more severe the instances of seasonal extremes become.
Incredibly, the last decade has seen three of the five warmest ever recorded springs in a record stretching back to 1659. The hottest of these was 2011. The first half of March was normal but by the last week, temperatures were over 10°C above normal every day. April was a true summer month with an average maximum just under 20°C. Between April 19-24th there was a major heat wave, with every day above 25°C and on 23rd, Easter Sunday, it was 27.4°C in London; no day in July was as warm. Unfortunately, Kate and William’s Royal Wedding day was the only cloudy day in this spell.
In contrast, 2013 was the coldest spring since 1883; blizzards blighted Britain throughout March, killing thousands of lambing ewes and the Isle of Man and western Scotland were buried under feet of snow and declared disaster areas. Some roads were closed for days by drifts 20 feet deep and frosts were relentless and severe for weeks on end – both north and south. April began bitter and snow still fell in London, remaining on high ground throughout the month and plaguing northern Britain with continued deep drifts, ice and frost. A May blizzard ravaged most of highland Britain and by May 1, even in the normally more clement south, not a leaf was on a tree, blossom was late and poor, daffodils failed to flower in many places and garden centres saw their worst spring sales ever.
The springs of 1837 and 1770 were even more extraordinary. Blizzards buried the N and E well into May and temperatures stayed below freezing even in London for several days in April accompanied by persistent snow, ice and frost. Lambing was catastrophic, crops could not be planted, budding fruit crops were killed off almost everywhere and staples were un-harvestable from frozen ground. Widespread famine and disease become serious issues, especially in Ireland, Britain, Germany and Scandinavia. This severity of cold was not uncommon in the period known as the Little Ice Age that lasted from about 1550 to 1900. This reached its zenith at the end of the 16th century, resulting in some bitter springs. From 1693 to 1700 spring seasons similarly as cold as 1837 happened almost every year and Scotland was colder than Iceland is now. The long economic blight this caused was a major factor in the union with England in 1707.
In 1947 the spring brought some of the worst and most widespread floods ever in Britain. Half a million British homes went underwater after two months of snow, often 20 feet deep, rapidly melted after heavy rain, in one of the wettest springs on record. After one of the driest ever winters in 2011-12, a spectacular reversal saw the spring become one of the wettest as torrential rain set in during April.
And at the other end of the scale 1893 brought one of the driest ever years and the worst ever spring drought. Hot sun and frost destroyed vast swathes of fruit crops in most regions and in London not a drop of rain fell for 93 days, from February to May. The spring of 1976 was hot and almost rainless in England, as were those of 1990 and 1938. Interestingly, the driest ever spring took place at the height of the great cold phase mentioned above in 1785 and was bitterly cold but clear and very dry. Until 2011 the desiccated spring of 1893 was the hottest spring on record, and almost certainly the sunniest, but the amazing 2011 season is now ahead in both regards.
Extremes in spring can happen suddenly. March 29, 1968 gave us the hottest ever March day at 25°C. Three days later snow swept across Britain and it was 0°C in London. March 1965 began with blizzards and deep snow; three weeks later there was a heat wave almost the equal of 1968. In 1989, March 31 saw temperatures in the 20s after a snowless winter; snow fell right across the south for the first time that year on April 5. Similarly, after one of the warmest ever winters in 1974-5, it snowed every day from March 16 to April 9, often causing widespread disruption even around London. That same year snow fell all the way down to Portsmouth on June 2nd, the latest ever known lowland snowfall in Britain.
Spring is perhaps the most diverse and fascinating season that we in Britain experience. But can science explain why its weather is so varied? It can. The warmer the oceans are, the more disturbed our weather is because this maximises the difference between the cold Arctic oceans and, in our case, the warmer North Atlantic; this difference is what generates rain and wind-bearing depressions. The seas are coldest in spring because of the lag time it takes the reduced sunlight and warmth of winter to lower sea temperatures. The cold water weakens the jet stream and high-pressure results. The character of our spring will largely be decided by where this high-pressure sits. Broadly, if it sits to the south it will be sunny and warm; to the east dry, dull and cool, and to the north and west it will bring cold weather. It may therefore disappoint you to hear that in 2015 high pressure has taken up long-term residence to the east of Britain which has led to a rather cool dull March. With any luck, however, it may soon move south.
Patrick is the author of "The Story of the British and Their Weather" which is out now!