Wet, but could be wetter!

As the rain hammers down again, it looks as if the monthly average for July could be exceeded by the end of today. In recent years there have been several quite wet Julys. In 2009 measurable rain fell on 22 days, and in 2007 over 124 mm of rain fell, including the 41mm that was recorded on the 20th. Some of the most intense rainfall of the year can fall in July, and large totals over a very short time period are not that unusual. Kensington had 25 mm of rain in 12 minutes on the 11th July 1927, and on the same day 37 mm fell in 18 minutes at Balham. On the 26th July 1946 there was a fall of 50 mm in 35 minutes at Kew. Some parts of Greater London have had over 100 mm in 24 hours and southeast London appears to be particularly vulnerable to these heavier falls. Over most of London it looks as if 1918 had the wettest July with parts of southeast and east London recording over 200 mm of rain. West London fared better with only 121 mm of rain at Kew, a figure this month is moving towards; but will it reach it?

A touch of optimism for July, maybe!

The general consensus is that this July has been poor so far. Statistics bear this out, with rainfall (up to the 10th) already 50% of the monthly average and temperatures the lowest for 23 years. The month has a long way to go and changes may occur. In some years they are marked. For example, in 1980, after a cool and wet June, holiday-makers were hoping for a better July. Alas, the first day of the month brought strong northerly winds, persistent rain and drizzle and a high of only 15. At midday in central London the temperature was only 12! A couple of dry and warmer days were then followed by more rain, and on the 8th another very cool, windy and wet day occurred with the 9th little better. No let up in the unsettled weather occurred until after mid month with infrequent sunshine and afternoon temperatures typically between 14 and 17. Finally, a sunny day occurred on the 21st, and although the maximum was only 19, it was the beginning of a spell of summery weather that lasted until the last couple of days of the month. On the 25th the temperature reached 28. Despite the warm end to the month, July 1980 was the coldest since 1922, and in recent years, although poor Julys have occurred, none of them have approached the dire weather experienced during the first 3 weeks of that very forgettable month.

July, the best summer month?

It can be argued that July is the best month of the year even though many of the high temperature records have occurred in August. Looking at the statistics for Morden, these covering the last 22 years, it would appear that day-time temperatures for July are 0.2 degrees warmer than those for August (23.3 against 23.1). Rainfall is 12mm less in July compared with August (43 against 55), in fact in recent years July averages out as the second driest month of the year behind March. All the summer months, along with May, only have 11 days with significant rainfall (0.2mm or more), but it's the subtleties that make July the best month. It hasn't the same number of very chilly days that can often spoil a June (Only 2 of the last 22 Julys have had maximum temperatures below 16, yet 17 Junes have had chilly days including a high of only 11.8 in 1998). August has had 2 years with maxima of 16, but in most years there is a distinct feel of autumn late in the month as the heat from the sun becomes less apparent. So, that's the argument for July, and today is a perfect example. Light winds, a mix of clouds and sun and a temperature of 24. Unfortunately, by Wednesday we'll be seeing the bad side of July weather!

3 fine days and a thunderstorm

George the Second (1683-1760) was unique in many ways. Firstly he was the last monarch to be born outside of the United Kingdom, secondly he was the last monarch to lead a British army into battle, and thirdly he was considered to be responsible for the adage that a British Summer was '3 fine days and a thunderstorm.' By co-incidence, a long-standing rainfall series for England and Wales commenced in 1727, the same year that he succeeded his father as king. During his reign he probably became aware of some exceedingly wet summer months. 1736 produced one of the wettest Julys ever known, and the Julys of both 1743 and 1751 were also thoroughly wet. Some wet Augusts occurred in the early 1730s, but perhaps it was the extremely wet August of 1737 that triggered the quote. We may never know, but there is certainly some truth in the saying, and as we enter day 2 of the fine spell (and the warmest day of the year so far!) , we wonder if the hot and humid day tomorrow will be followed by that traditional thunderstorm!

Good for the garden...in moderation!

Rain is almost a daily occurrence this month, and although it has done wonders for the garden, it is now becoming somewhat excessive. So far, this June has had nearly 66mm of rain making it the wettest this century. It has a long way to go before beating the 137mm that fell in June 1997. Nevertheless, there has almost been twice as much rain as we had in the whole of the Spring (March, April and May). Whilst the fruits are filling out quite nicely, the temperature is on the low side for some crops, especially tomatoes. At the moment it is the coolest June for 20 years, although there is a hint of somewhat warmer weather later in the month. The highest daily average temperature occurred in April with 19.3C. May had 18.6C, and so far this month the average is 19.1C. It would be extremely unusual if this situation was unchanged at the end of the month, and it would be even more unusual, perhaps unique, if the highest temperature (27.2C on the 23rd April) turned out to be the warmest day of the year!

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.