A cold April for a change

It's now half way through the month and there is every indication that we are in for a colder than average April. In fact it could be the coldest April since 1989 although a lot can happen in 2 weeks! In recent years we have had many warm Aprils. Last year there was record-breaking warmth during April and, excluding this month, the 3 warmest Aprils since 1900 have occurred in the last 5 years. Looking at the top 10 coldest Aprils in this area since 1900 the only ones in fairly recent years that have featured are 1986 and 1978. Most of the top 10 (6 entries) are made up of Aprils from the first 30 years of the 20th century. The coldest April of all was 1917. To put that April into perspective, the mean temperature was 6.0 Celsius, compared with 8.2 Celsius so far this month (last April, 2011, we had a mean temperature of 13.6 Celsius). It looks as if both the April of 1917 and this month were/are showery months, but it was noticeable that up on Hampstead Heath there were 13 days when sleet or snow was observed and grass frost occurred on 26 nights. So, the air was obviously cold, and in that year the temperature didn't rise above 15 Celsius until the very last day of the month. We' already had 16C!!

There is still time!

The crab apples are beginning to rot on the trees and so far there has been no sign of the Redwings or Fieldfares that descend on the tree when there is 'real' winter weather. There still hasn't been any 'proper' snow and the days are steadily lengthening. The forecast charts occasionally hint at a blast from the east but without much conviction, although there is still hope. Some of the coldest Februaries have been proceeded by average, or even mild, Januaries. In 1947, the coldest February since 1900, was preceded by fairly mild weather up until mid January. In 1986, the second coldest February since 1900, the preceding December was less snowy than December 2011! There were just 2 days with a few blobs of sleet. January 1986 was a wet month with temperatures close to average. Sleet or snow fell on 8 days but it didn't settle. The last week of January became rather cold and winds swung to the northeast and then February! The first few days of the month were dull and drizzly although a little snow settled on the evening of the 2nd. Real winter began on the evening of the 5th. Snow fell followed by a frost, and snow then remained on the ground until the 5th March with every night during that period having a frost. Time will tell!

Soft January days

At the moment, with a third of the month gone, this January is the mildest since before 1900. It hasn't been wall to wall sunshine, but the soft grey clouds with chinks of blue showing through are nevertheless uplifting when accompanied by a temperature that frequently tops 10 Celsius. Since 1900, a total of 4 out of the top 10 mildest Januaries have occurred during the last 10 years and only 2 of the mildest Januaries occurred before 1974. The mildest January, 2007, had maxima above 10 Celsius continuously from the 3rd to the 20th, and on 6 days the high topped 13 Celsius, a figure we haven't reached this January. The highest value was 14.2 Celsius on the 18th, a day of destructive winds when a gust of 58 knots (64 mph) was recorded here. Although the month was record-breakingly mild, it was not without its wintery moments. Sleet or snow fell on 5 days towards the end of the month and on the 24th there were 3 centimetres of snow carpeting the garden for most of the morning.

A very mild Christmas

At this time last year we were just emerging from our biggest December freeze for 120 years. Snow lay on the ground. albeit in the form of large icy patches, and after a maximum temperature of just minus 0.9 Celsius on Christmas Day, Boxing Day dawned with a low of minus 6.8 Celsius. This December, mild, but unremarkably so, has not seen temperatures anywhere the values recorded last year. Yesterday (Christmas Day) was the mildest in this area for 13 years, and today, with the temperature nudging 13 Celsius, is also the mildest Boxing Day since 1998. Last year, the temperature failed to rise above 10 Celsius during the whole of December, but for snow lovers the rest of the winter was a dismall failure. A few flakes of snow were observed in the rain on 3 days during January and no snow fell in February. So what of the rest of the winter of 1998/1999? Apart from a brief snowy spell at the beginning of the second week of February, southwesterly winds prevailed bringing plenty of mild changeable weather; and this winter?........

No snow......yet!

The Christmas trees are all lined up ready for the festivities, but this year it's looking as if the Christmas period will be green, as it usually is of course! On this day last year the temperature reached 8 Celsius, but it was also the first day of the month with no snow observed in the garden. The snow returned on the 16th, and although it was not a 'true' white Christmas with snow falling, there was enough of the white stuff around to produce a supply of icy snowballs. A white Christmas with snow falling is much rarer than a December without snow falling. There has been some snow falling in the last 3 Decembers, but prior to that 4 out of 6 Decembers were completely free of snow. Also, the definition of 'snow' to the meteorologist is any preciptation that contains snow flakes whether partially melted on not. So, a cold and wet day with the odd blob of very wet snow is registered as a 'day with snow' . It remains to be seen if this December gets it's day of snow, but in the last 40 years there have been 16 snow-free Decembers in this area. The odds of seeing snow this month are good.....but not very good!

Another mild and sunny day

November 2010 was a fairly dry month, but that is the only weather feature it shared with this November. So far this month there have been no air frosts, although tonight could change that statistic. There have been several mild and sunny days, a continuing characteristic of this autumn, and although the leaves have fallen off most of the trees, the run up to winter is very different from last year. On this day in 2010, it was cloudy, not unusual of course, but the maximum temperature was only 1.4 Celsius. That is 12.7 Celsius lower than the highest temperature recorded today. Although a frost is a possibility for tonight, the minimum will undoubtedly be several degrees higher than on the corresponding night last year. On that night the temperature fell to minus 5.9 Celsius, the lowest November reading for 21 years. On the last day of the month there was heavy snow, and the good folk of this area awoke on the 1st of December to an 8 centimetre covering of snow! Not so this year, presumably.

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.