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!

Second Best

The frost has left the banana looking sad but all the talk is about the warmth of November, the autumn and the year. In this area, November 2011 was the 2nd mildest since before 1900, the autumn (September, October and November) was also the second warmest since 1900. Currently the year 2011 is also the 2nd warmest since 1900! So, what does December need to make it number one. The year to beat is 2006. January and February were actually milder this year than in 2006 by about 1.5 degrees. The spring was much warmer this year by about 3 degrees. However, the summer was much cooler by almost 4 degrees. This autumn was less than a degree cooler than the autumn of 2006; so where does that leave the last month of the year. December 2006 was mild with a mean temperature of 7.7 Celsius. In fact, that made it the 5th mildest December since 1900. For 2011 to be the warmest year since 1900 this month needs to have a mean temperature of 8.6 Celsius. In December 1974 the mean temperature was 8.7 Celsius so the figure is achievable, but this year? No, pretty unlikely, second best again!

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 Fog Myth

The fog which descended over parts of London and persisted through much of Sunday helped to fuel the myth that London is a foggy city. Certainly the pea-soupers that plagued the Capital in the past justifiably gave the city a bad reputation. The polluted fog of early December 1952 was probably responsible for over 4000 deaths in Greater London and this eventually led to the Clean Air Act of 1956 and a decline in the instances of choking fogs. Nowadays, the heat island of London helps to reduce the number of 'natural' fogs and the few fogs that do occur are usually confined to, or are at their worse in, low-lying suburban areas of London. The statistics for Morden show that since 1988 November, on average, has been the foggiest month. However, a day with fog (defined as a day when visibility is below 1000 metres at 0900 UTC) has only occurred on 19 occasions, and the highest number of foggy days in any month has only been 4. Thus the 'foggy London' tag has well and truly been laid to rest.

What about the frost?

This autumn, so far, has seen a couple of white grass frosts (in October) but no air frosts have occurred. How unusual is that? At this site records began in 1988 and since then there have only been 2 instances where the autumn months, September, October and November, have been completely free of air frosts. The years in question were 1994 and 1999. In 1994, November was exceptionally mild and currently stands as the mildest November in this area since before 1900. Also the temperature difference to the next mildest (1938) is, in statistical terms, quite substantial. However, at the moment, this November is milder than that of 1994, also by quite a significant margin. Today may help to change that, though, with the maximum temperature struggling to achieve double figures. In both 1994 and 1999 the frost-free period did not extend through the remainder of the year. In 1994 the first frost of the 'winter' occurred on December 15th with the 14th seeing the first frost in 1999.