Although April 2005 was a changeable month with above-average rainfall in many parts of the UK, a large part of the London area was actually marginally drier than average. This extends to six months the present dry spell in the capital. As we enter the summer half of the year when evaporation routinely exceeds rainfall there is now some concern about water supplies during the next several months in this heavily populated part of the country. Of course, a cool, changeable summer would lessen demand and relieve some of the pressure on supplies, but a long hot summer would exacerbate the situation. Figures for the last century or so at Kew/Heathrow indicate that the November 2004 to April 2005 period was the driest in the London area for almost 30 years:

2004-05 192mm
1975-76 146mm
1953-54 156mm
1943-44 178mm
1933-34 141mm
1928-29 165mm
1901-02 191mm

The statistical return period for the 6-month period Nov-Apr is 9.3 years.

The national picture is rather different. Averaged over England and Wales April was a rather wet month, and this has further diminished the newsworthiness of the England-and-Wales statistics for the present dry spell. Six-month totals for November 2004 to April 2005 inclusive give the following:

2004-05 361mm (73%)
1996-97 358mm
1975-76 286mm
1953-54 341mm
1948-49 355mm
1943-44 313mm
1937-38 321mm
1933-34 312mm
1928-29 326mm
1920-21 346mm
1917-18 354mm

The return period for the six-month period Nov-Apr is 6.5 years.

© Philip Eden