Why has it been such a miserable summer? Is it global warming or, after tomorrow, will we be able to blame a ninth-century English bishop?Brendan McWilliams reports
Heaven help us if it rains again today! The heavenly reference is not a mere colloquialism, but a reminder that this is St Swithin's day, with dire consequences should there even be a shower. In a nutshell:
Saint Swithin's day if it do rain,
For forty days it will remain;
Saint Swithin's day if it be fair, For forty days 'twill rain nae mair.
To be accurate, we are not fully certain that Swithin really is in heaven. He is not a saint in the strictest sense, never having been formally canonised, but is one of those on whom the prefix was popularly bestowed without the formal endorsement of St Peter's.
He was however, a devout Bishop of Winchester, renowned for his humility, who died in AD 862 leaving instructions that he was to be buried outside his cathedral "in a place made vile both by the feet of passers-by and the raindrops falling from the eaves".
There he lay for more than 100 years. When miracles came to be performed in his name, however, and the income from visiting pilgrims grew more lucrative, the monks came to think of it as scandalous that such a holy man should rest in such a lowly spot. They prepared to move him to an opulent shrine inside the cathedral, the day appointed being July 15th, 971.
According to legend, a tempest raged that day and the removal was postponed. For 40 days and 40 nights it rained and rained, until the monks, realising the folly of trying to thwart a saintly whim, decided to leave the humble bishop where he was. History tells a slightly different tale, but the weather legend has survived.
The Swithin superstition is English, but something similar is found in many European countries. In Scotland, for example, St Martin controls the weather for 40 days from July 4th, while in Germany the traditional date is July 27th, Siebenschlaefertag or the feast day of the Seven Sleepers of Ephesus.
The superstition may be related to the view held by many meteorologists that by around mid-July each year, most European summers have settled down to a pattern which often persists for the remainder of the season - either cool, wet and changeable or mostly warm and sunny. If this be so, the general character of the weather around St Swithin's day may not be too bad a guide as to what to expect for the remainder of the summer.
Over the last six months, February brought nearly twice the normal rainfall; March was dry enough, but rain in April in many places was 150 per cent of normal and May and June were very similar.
As the downpours continue, we have experienced so far this year nearly 75 per cent of the rainfall we might reasonably expect for the entire 12 months - despite the fact that the period from April to June inclusive is statistically the driest period of the calendar.
The immediate reason for the poor conditions is readily identified. Normally at this time of year an area of high pressure semi-permanently resident in the vicinity of the Azores extends northwards for at least a week or two, giving us a spell of dry, settled weather.
So far in 2002, this has resolutely failed to happen. Instead, the relentless procession of Atlantic depressions, swept eastwards in our direction by a steady stream of westerly winds at upper levels, has continued unabated. Moreover, from time to time in recent months, the westerly flow aloft has developed a kink or trough in the vicinity of Ireland.
A surface depression which encounters such a feature will often find it rather comfortable and will hesitate beneath it to perform a pirouette or two; for the duration of its indecision it deposits even greater quantities of unwanted rain on the soggy landscape underneath.
Also in rainy conditions, as a general rule, the higher the surface temperature the heavier the rain; although it may not seem so, it is warmer now than earlier in the yearso the rain when it comes is often that bit heavier.
If there is one thing that meteorologists like more than telling people records have been broken, it is reminding everyone that it has all happened before. During the Nineties, 1993 stands out as having had a very wet, miserable summer, and the year as a whole turned out to be the wettest in Ireland since the mid-1960s. In the mid-Eighties, we had several poor summers in a row, but without a marked improvement, 2002 seems likely to set even more impressive records.
Nowadays we tend to blame ourselves, assuming that the great amounts of carbon dioxide and other greenhouse gases that we inject into the atmosphere must be the cause of our misfortunes. It may well emerge that the incessant rains are not entirely unconnected with the gradual rise in global temperature, but it takes a great and quite unjustifiable, leap of the imagination to blame global warming for a few wet months in Ireland.
Nonetheless, the statistics of 2002 will be carefully dissected to see if they fit some pattern that we really ought to be concerned about. In the meantime, let us not concern ourselves too much with Swithin. As the 18th-century poet John Gay counselled:
Let not such vulgar tales debase thy mind
For neither Paul nor Swithin rules the clouds and wind.