Summer coming to an end

Like it or not summer is coming to an end, at least meteorologically speaking. The 3 calendar months, June, July and August constitute summer but hopefully there will be plenty more 'summer-like' days to come during the autumn. With 10 days left until the end of the month it looks, assuming that there will be more than 10mm of rain before the 31st, as if this summer will be rated as the poorest since 1988. So how poor was that summer compared to this one. Firstly, in June 1988 there were only 25mm of rain against 82mm this last June. There were only 9 days with rain falling but in June this year there were 17 rain days. However, in June 1988 there were 18 days when the temperature failed to reach 20 C., but this year there were only 16 cool days. In July 1988 there were over 65mm of rain measured compared with 52mm this year. The rain fell on 17 days in 1988 but only on 12 days this year. There were 15 days with maxima below 20C in 1988 but only 10 days this year. August 1988 was not wet, just 29mm recorded but temperatures failed to reach 20C on 9 days. So far this month we have had over 30mm of rain but temperatures have only failed to touch the 20C mark on 3 days. It's still possible that this summer will descend to the level of 1988, but probably not.

So, how bad is this summer?

The summer is about two thirds over and there are two schools of thought as to how it is progressing. Some think it is very pleasant with good growing weather. Others think it is cool and wet. Statistics point towards the latter claim....but with reservations! It has been said many times that the manipulation of numbers can often produce the results you want to see and the following figures come with the same caveat. By using a ranking system from 1 to 112, with 1 being the warmest or driest since 1900 and 112 being the coolest or wettest since 1900, comparisons can be made. For example, June and July 1976 were both warm and dry. Using equal weighting, June 1976 produce 1+6=7 and July gave 8+16=24. The total therefore was 31. By way of contrast, the June and July of 1987 were both very poor and produced 86+86=172 for June and 56+92=148 for July, a 2-month total of 320. So far, the numbers for June are 67+94=161 and for July 90+59=149, a total of 310. It can be seen that using basic comparisons of temperature and rainfall, the first 2 months of this summer are up there with the worst of them! Let's hope that August 2011 is less forgettable than the early months of summer.

Rain, and more rain

With the drought stories fading from the news as quickly as they appeared, rain drops continue to fall. Of course, some parts of the country are still in dire need of sustained rainfall, but for this area of south London the drought is well and truly broken. So far this month we have had over 45mm of rain. Already it is the wettest June for 4 years, and the wettest start to June since 2002. In that year 42mm fell in just 1 day (the 5th), and back in June 1973 nearly 45mm fell in Morden in 1 day. Recently, Junes have tended to be dry and there have only been 2 wetter than average June since 2000, Prior to that, there were a couple of exceptionally wet Junes. In 1998 nearly 125mm of rain was recorded, and in the previous June (1997) over 137mmwas measured. Although 1997 possessed the wettest June in living memory, in 1903 over 180mm of rainfall was measured at Kew, all of it falling between the 9th and 20th. At Carshalton over 80mm of rain fell on 10th June 1903. By the way, most of the rest of that Summer, and much of the Autumn, remained cool and wet!

1976 and all that

The grass is beginning to turn brown quite widely, just as it did during the summer of 1976. If the media were to believed in those hot and dusty days England would never again be a green and pleasant land. Of course, the rain arrived in spades late in August and through September. By the end of autumn, there was little to show for the prolonged dry spell. Aside, that is, for a few dead trees, most of which weren't native to southern England. So, where does it leave 2011? Although, it was the driest Spring this year in living memory and beyond in this area, the winter was fairly wet. Already this year we've had over 50mm more rain than we had in the first 6 months of 1976. Also, the weather patterns showed marked differences between the Springs of 1976 and 2011. As a result temperatures are very different. March 1976 was cooler than March this year with no days exceeding 16 Celsius (5 this year). April 1976 had near normal temperatures compared to the record-breaking warmth this year. By way of contrast, May was fairly warm in 1976 with the temperature exceeding 29 Celsius as early as the 7th. Although this May was reasonably warm there were no hot days. June 1976 was outstandingly warm, and although the maximum temperature today is around 27, a decline into maxima mediocrity seems imminent.

Today marks the 15th consecutive day without measurable rain (defined as 'no daily rainfall equal to, or exceeding, 0.2mm/0.01 ins.'). Up until the 1980s this 15-day period was known as a 'drought'. However, the rise of the mocking tabloid press, the general decline in exactitudes, and comparisons with life-threatening water shortages in the Third World quite correctly brought about the abandonment of the term 'drought' by all but a few diehards.

Nevertheless, it's interesting to examine these lengthy dry spells. The previous one occurred here from the 16th September to 2nd October 2009 (a total of 17 days), but lack of rain is generally less common during the Autumn and Winter months. A good Summer often produces a prolonged period of dry weather. In 1959 this area had 37 consecutive dry days (15th August to 20 September) and in 1976 parts of southwest England had no measurable rain for 45 days. Perhaps surprisingly there was no 15-day dry spell in 2003, but the rainfall deficit for the period February to October in that year was well over 50%.

The Spring months seem to have the most frequent dry spells. In recent years there have been several in mid Spring. In 1995 there were 19 dry days (29th March-16th April), in 1997 it was dry from the 25th March to 17th April (24 days). A total of 27 dry days occurred between 21st March and 16th April 2002, and in 2007 there was dry weather between 31st March and 22nd April (23 days).

Is there any way of connecting dry Aprils to the following Summer? Fortunately the answer is no. In 1912, parts of London had no measurable rain during April and the following Summer was one of the coldest and wettest on record! By the way, the previous 4 mid Spring dry spells were equally divided between good Summers and decidedly indifferent ones.

A barbecue summer

As the baying pack from the media continue to taunt the rather disingenuous attempt by the Met. Office to tell us it almost is a 'barbecue summer', let's find a few facts ........at least for this part of the country where 15 million potential barbecuers live.

There is a reason why barbecues are more common in Mediterranean countries and the USA than here. They have warm and dry summers, and we don't. Up until the mid 70s plastic macs donned for a trip to the pub were more common than plastic plates and cups on the patio, but then the summer of '76 arrived. The general public realized that the sky didn't leak every day, and suddenly al fresco hit London. The barbecue grills rusted for a while in the late 70s and 80s, but from the end of the decade onwards a barbecue grill became a 'must have' along with the 4-wheel drive and a mobile phone. In many years the weather co-operated, but in this summer, like in its two predecessors, plastic mac days returned.

The official statistics put an emphasis on the mean temperature and the total rainfall, but if the nights are cloudy and windy they're often milder than after warm and sunny days. Perhaps more relevant are 'days' with rain falling and daily maximum temperatures, and these paint a poorer picture of the summer weather so far this year.

May, perhaps perceived as a tad early for a trip outside, did produce a few reasonable days during the last week, and June was a pleasant month in London. However, using maximum temperatures, it ranked cooler than the recent Junes of '76 , '89, '92, '96, '03, '04 and '06. Although rainfall totals were below average, the number of days when rain was recorded was above normal

For many people in Southeast England July was a poor month. After the 2nd, winds were from the southwest on nearly every day. The breezes were brisk at times and on the south coast they were often fresh or strong. The temperature has failed to rise above 21 Celsius since 3rd July on the Sussex coast, and although it has been somewhat warmer at times inland, in south London there have only been 4 cooler Julys (based on maximum temperatures) in the last 20 years! The other interesting statistic is with regard to rainfall. Okay, it was a wet month around London, but not exceptionally so. However, measurable rain fell on 20 days.....4 more than the previous July record during 20 years of observations, and what's more 6 of the remaining 11 days had some rain, but not enough to measure.

The Met. Office have 'revised' their forecast for the rest of the summer, but while they keep digging their hole, it remains to be seen if nature has the last laugh and produces a warm and dry August.

That magic 70 mark

April was the 3rd warmest in this area since before 1900, BUT, the temperature failed to reach 70 Fahrenheit (21.1 Celsius), the much quoted value favoured by the tabloid media. So far, the maxima have not exceeded 21 Celsius this month either, and that is more unusual. In 20 years of records in Morden, the temperature had always reached 21 Celsius by this time of year. As the blustery northeast wind continues to bend the trees under cloudy skies, there seems little prospect of higher temperatures in the immediate future. A scan through the records reveals 1975 as the last year when the temperature stayed below 21.1 Celsius until the end of May but, after a cold start to June, that Summer became very good. Prior to that, the year 1972 had no maxima above 21 Celsius by the end of May, but the June of that year also had no highs above 21 Celsius! The June of 1972 was the coldest of the century, and the rest of the Summer, although dry, was unpleasantly cool.