The heaviest snow in South London since.....

The 19 centimetres of snow that fell yesterday and overnight has got us trawling through the record books. 'The snowiest since February 1991' is a typical quote from the media, but in that month, the Morden area only had 16 centimetres of level snow. Back in January 1987, it was bitterly cold and there were some deep drifts, but again the level snow was only 16 centimetres. Snow stayed on the ground for a while in the winter of '81/82 but not particularly deep, and then it's back to the 'winter of discontent' - 1978/79. Certainly on hills, and particularly in north London, snow depths exceeded 20 centimetres, but not in Morden. Early March produced depths close to 15 centimetres, but December 1962 had heavy snow on Boxing Day http://www.london-weather.eu/article.102.html, followed by further significant falls later in the month. The resulting depth was 25 to 30 centimetres. That's where the record lies.... so far!

'Snow Breaks the Drought'... but not any more

The light snow that fell overnight and early this morning marked the end of a 16-day period without measurable rain. In the old days, when City gents wore bowler hats and Christmas crackers only came from Woolworths, a spell of 15 days, or more, without 'significant' rain (less than 0.01 inches, or 0.25 millimetres) was known universally as a 'drought'. It was a term reluctantly used by meteorologists but regularly dug up by the media. Fortunately, since the real droughts, especially in Africa and Australia, have been vividly portrayed on our television screens, a lack of rainfall has been taken more seriously. However, to get back to the quirky old 'drought'. There have only been 3 occasions during the last 20 years in this part of London when a 15-day dry spell has encompassed the winter months (December, January and February) and not at all when the majority of dry days occurred during December! The 16 consecutive 'dry' days is nowhere near a record. In 1959, http://www.london-weather.eu/article.99.html central London had no measurable rain from the 24th January to 20th February, a total of 28 days.

Wettest day of the year in London?

Yesterday was the wettest day of the year with 25.4mm (exactly 1 inch) of rain falling in the 'Rain day' that stretches from 09 to 09 GMT. It was not a record breaker, nearly 32mm fell in December 2002 and almost 30mm fell in 1995. Boxing Day 1886 appears to have been the wettest December day, but as some of the totals included melted snow a cynic may question the validity of the readings. The numbers for that day included 46mm for Kensington and Brixton and 60mm for Hampstead. In recent years, 34mm fell in parts of southwest London during December 1979. Interestingly, the whole rainfall event this December covered 2 'Rain days' and the total came to nearly 36mm. It commenced around 0100 hours on the 13th and then rained continuously until 2300 hours, a total of 22 hours. That in itself is not a record. During June 1903 parts of north London had over 58 hours of continuous rain. By the way, a few days after that rain a three week 'drought' commenced!

Sunny Weather in London

After 3 dull days the sunshine that arrived today was to be welcomed. If it wasn't for a few minutes of low cloud at either end of the day the sunshine could have been unbroken. The 1st of December is potentially the sunniest day of the month with the daylight fractionally longer than on any other December day. This potential is seldom realised of course, but in 1954, a mild and sunny December occurred, and there were 7 hours of sunshine on the opening day. Two years later it was also mild during December but there were only 9 hours of sunshine all month. The Clean Air Act of 1956 helped to reduce pollution in London and smog is now almost unheard of. Fog is also a rarity now in Greater London, and the dreadfully dismal months of the 19th and early 20th centuries are behind us. There will probably never be a repeat of December 1890 when much of London had less than 30 minutes of sunshine all month, and parts of the West End remained completely sunless.

Wettest day since......?

Yesterday (10th November) nearly 24mm of rain fell. This made it the wettest day of the year so far and the wettest day since November 19th last year. November ranks, on average, as the wettest month of the year in many parts of the country, but in the last 20 years, in this area, October has been a wetter month. A daily rainfall total of 24 mm in November is actually not uncommon here. It has occurred 4 times during the last 20 years, and 3 of those occasions have been during the last 8 years. On each of the last 3 very wet November days, more than 30 mm of rain have fallen. The wettest day was the 5th November 2000 with 33 mm of rain. The wettest day in the area from historic records appears to have been the 25th November 1938 when nearly 42mm of rain was measured.

Frosty October Nights

The grass temperature fell to minus 5 last night, the 8th 'grass frost' of the Autumn so far. The minimum temperature forecasts published in newspapers and featured on radio and television broadcasts are, quirkily, based on the expected temperatures in a louvred white box standing in an open position between 1.25 and 2 metres above the ground. Anyone small enough to be sitting in one of those boxes last night would have experienced a temperature of minus 0.3 Celsius, making it the first air frost of the season. During the last 20 years there have been 12 years when air frost was absent during October, but in 1997 air frost occurred on 5 nights during October. The earliest frost was on the night of the 15th/16th October 1993, but in the suburbs of London frost has occurred much earlier in past years. Aside from the notable frost hollows at Chipstead (Surrey) and Rickmansworth (Hertfordshire), one of the earliest suburban air frosts occurred on the night of the 18th/19th September 1952. There was also a frost in southwest London on the 29th/30th September 1919. In October 1888 there were 9 or 10 air frosts across much of London. The lowest October temperature recorded in Morden during the past 20 years occurred on the night of the 29th/30th 1997 when a minimum of minus 5.0 Celsius was measured. A value that could be hard to beat.....maybe!

Last of the Summer Days?

Time to get the potatoes in before Autumn truly arrives. Although temperatures above 20 Celsius in October are not unusual, after the disappointingly cool September in London, this short warm spell is much welcomed. The maximum temperature of 22.2 Celsius today is over 1 degree warmer than any maxima recorded during September, and is the highest this late in October since 2001. There were only 4 days during August that were warmer, 13 days in July and 7 in June. In October 1921, the first 11 days of the month had maximum temperatures above 21 Celsius, and on the 5th and 6th of October in that year the high was close on 29 Celsius at several places in London, including Kensington Palace, Greenwich, Camden Square and St James's Park.