UK’s exceptional weather in context

6 02 2014

As the UK’s run of exceptionally wet and stormy weather continues, the Met Office’s National Climate Information Centre has looked at how the last two months compare in the historical records.

Here’s some facts and figures for the weather we’ve seen through December and January:

For the UK

  • For the UK, December was provisionally the equal-fifth wettest December in the national series dating back to 1910 and January was the third wettest January in the same record. When the two months are combined, it is provisionally the wettest December and January in the series.
  • There were more days of rain (any day with more than 1mm of rainfall) for the UK in January than for any other month in a series dating back to 1961, with 23 days.
  • It was the windiest December for the UK in records back to 1969, based on the occurrence of winds in excess 60 kts (69mph).

England and Wales

  • Looking at the England and Wales Precipitation series, which dates back to 1766, it has been the wettest December to January since 1876/1877 and the 2nd wettest overall in the series.

Scotland

  • December was the wettest calendar month on record for Scotland in the series to 1910.
  • For eastern Scotland, December and January combined was provisionally the wettest two month (any-month) period in the same series.

Southern England

  • There have been very few dry days in this area since 12 December and regional statistics suggest that this is one of, if not the most, exceptional periods of winter rainfall in at least 248 years.
  • Despite the rainfall being concentrated in the second half of the month it was the wettest December for south east England since 1959.
  • January was the wettest January for the south England region in the national series dating back to 1910, and the wettest calendar month for the south east region in the same series by a huge margin.
  • The two-month total of 372.2mm for the southeast and central southern England region is the wettest any 2-month period in the series from 1910 .
  • From 12th December to 31st January parts of south England recorded over five months worth of rainfall (based on average January rainfall for the region).

You can see more statistics on recent weather and through the historical records on our UK climate pages.

Full month provisional statistics from January 2014:

Mean Temperature Sunshine hours Rainfall  
January
Actual Diff from Avg Actual % of Avg Actual % of Avg
  degC degC hours % mm %
UK 4.8 1.1 44.8 95 183.8 151
England 5.4 1.3 57.3 106 158.2 191
Wales 5.3 1.2 38.0 78 269.0 171
Scotland 3.5 0.9 27.2 76 205.3 116
N Ireland 4.5 0.3 37.3 84 170.7 147




Is 2012 the wettest year on record?

31 12 2012

We announced last week that 2012 is already the wettest year for England in our records dating back to 1910, but we’re still waiting to hear whether it’s the wettest on record for the UK.

The latest figures we have for 2012 go from 1 January to 26 December, and show that during that time we’ve had 1291.2 mm of rain for the UK – meaning it is currently the 4th wettest year on record.

It’s 46.1 mm short of the record of 1337.3 mm, set in 2000, so if 46.2 mm of rain falls between 27-31 December we will have a new record.

It’s likely to be fairly close-run, but it’s impossible to say whether 2012 is a UK record for rainfall until all the data come in from our weather observation sites around the country.

This information should come in on the 1st and 2nd of January, then all the data will need to be processed and we expect to have a provisional answer on Thursday, 3rd January.

We’ll post the news here on our blog as soon as all the provisional statistics for 2012 come in.





Cold night breaks August records in places

31 08 2012

Last night saw some unusually cold August night-time temperatures across parts of the UK, with some observation sites hitting record lows.

Among those stations seeing their coldest recorded August temperature were:

Braemar No 2, Aberdeenshire: -2.4 °C

Aviemore, Highlands: -1.8 °C

Redesdale Camp, Northumberland: -0.7 °C

Bainbridge, North Yorkshire: 0.5 °C

Benson, Oxfordshire: 2.1 °C

Bradford, West Yorkshire: 2.8 °C

Observation sites have operated for differing amounts of time, so some records are more significant than others. Out of the new records, Bradford has the longest historical dataset – going back to 1908.

It’s worth noting that none of these break the all-time record low UK temperature for August, which is -4.5 °C recorded at Lagganlia, in Inverness-shire on 21 August 1973.

Why was it so cold in places?

Last night saw northerly winds drag cold air from quite a long way north over the UK. This air was also dry, which meant there was very little moisture to help retain heat from the day.

This, combined with clear skies caused by the high pressure sitting over the country, meant all the heat radiated into the sky – leaving very cold temperatures for the time of year.

Once in a blue moon?

While UK weather records such as this aren’t broken once in a blue moon (we’ve had many broken already this year), this set does more or less coincide with the astronomical phenomenon.

A blue moon occurs when there are two full moons in one month – which is perhaps not as rare as the saying may have us believe. There was a full moon at the start of August and now a full moon is due tonight.

You can read more about this in articles online, such as this one at earthsky.org





Is it the wettest UK summer on record?

26 08 2012

This summer started with the wettest June in the UK in the national records which go back to 1910 and was followed up by a wetter than average July (16th wettest), so are we set for the wettest summer on record?

Officially, in meteorological terms, summer runs from the start of June to the end of August – so there are still a few days to go for this year.

The Met Office holds many different climate datasets but uses the UK national series that goes back to 1910 when referring to records.

In this dataset, the record to beat was set in 1912, when the UK had 384.4mm of rain – although we don’t have to look too far back to find a very wet summer, as 2007 is third in the rankings with 357.8mm. The 1971-2000 average for the UK in summer is 226.9mm.

Looking at this year, we have the figures for June and July, but for the UK as a whole we currently only have data up to 15 August – which show rainfall had been slightly below average to that point.

That means we can say with some certainty that we have seen 300.8mm of rain so far this summer (145.3mm in June, 115.9mm in July, and 39.6mm to 15 August), ranking 20th in the records.

There has been a fair amount of rain since then, so that ranking is sure to have climbed – but it’s not possible to say until all the numbers have been crunched at the end of this month.

It’s important to remember that the UK total rainfall is effectively an average of the rain that falls across the whole of England, Wales, Scotland and Northern Ireland – so looking at one station, or even one country, isn’t a reliable indicator of how much rain we’ve seen for the UK as a whole.

We can say that this summer is likely to be one of the wettest on record – some may argue that, as it’s already in the top 20% in records dating back to 1910, it already is one of the wettest on record.

We can also say that this year has continued a disappointing run of UK summers which started in 2007 – all of which have seen above average rainfall and, with the exception of 2009, below average sunshine hours.

However, we cannot say where this year will finish in the rankings or whether it will challenge the record set in 1912. For that final assessment, we’ll have to wait until after the end of August.

You can see a discussion about the causes of this year’s unsettled summer in an article posted earlier on our blog.





Is this the wettest June on record?

26 06 2012

Update: Provisional Met Office figures for the whole of June are now available at: Met Office confirms wettest June in over a century

We all know that, so far, it has been a very wet June in many parts of the UK – but just how wet has it been?

Met Office figures show that, up to the 24th of the month, the UK had seen 122.3 mm of rain –ranking as the third wettest June since records began in 1910 and well over one-and-a-half times the UK average.

So this month is currently just behind the second wettest June in 1912, which saw 124.5 mm of rain, and a little way off the wettest June in 2007, which saw 136.2 mm.

Clearly there are several more days to go and there is some rainfall in the forecast, so not possible to categorically say exactly where the month will finish in the overall records – however it is safe to say it has been a disappointingly wet month.

It’s important to note the rainfall this month hasn’t been evenly spread over the UK. Some areas have seen a great deal of rain, with 52 observation sites breaking record rainfall totals.

Not all of these records are significant as some of stations only have a very short history – for example, Usk in Monmouthshire has only been taking measurements for one year. However, at the other extreme, Otterbourne in Hampshire has been operating for 119 years.

While some areas have already seen record rainfall, others are lingering close to their all-time June minimum. Six stations are currently still below their lowest June rainfall total – but this could change by the end of the month.

What is interesting as that most of the drier stations are in the far north and west of the UK – areas which we would normally expect to see the most rainfall.

UK rainfall map

Map showing rainfall up to the 24 June 2012 compared to the1971-2000 average. Many parts of the country have seen double their normal amount, while the far north west has seen much less than usual.

 

This illustrates the story behind this month’s weather, as the rain-bearing low pressure systems moving in from the Atlantic which normally track to the north of the UK have been taking a much more southerly route, soaking parts of the south while the far north west has remained unusually dry.

One of the main reasons for this is the position of the jet stream. This is a narrow band of fast flowing westerly winds (ie blowing from west to east) high in the atmosphere.

This band moves around and changes its track, and where it sits can impact the UK’s weather. When it flows to the north of the country it can guide low pressure systems away from the UK (but they often clip the far north west of the country as they pass by).

Throughout this June the jet stream has had a much more southerly track, allowing those low pressure systems – with their wind and rain – to come straight over the UK to bring heavy rain to more southern areas while the north west remains relatively unscathed.

You can find out more about the jet stream in our YouTube video.





Definitely May-be an average month

30 05 2012

After a particularly cold and wet start, followed by a dry and exceptionally warm spell, May could be seen as anything but average.

However, the early monthly figures tell a different story – statistics from 1st to 28th of the month show temperature, rainfall and even sunshine are very close to normal.

This May is a stark example of why it’s difficult to judge a month at its halfway stage.

Up to the 15th the mean temperature for the UK was just 8.1 °C, 1.9 °C below the long-term (1971-2000) average.

Rainfall was running at 79% of the average too, well ahead for just halfway through the month, and sunshine was behind at just 41% of the average. This tells the story of a wet, gloomy and cold 15 days.

But around the 20th the UK’s weather changed its mood – giving way to a run of dry and fine weather, with some remarkably high temperatures.

This included a new maximum May temperature for Scotland – with 29.3 °C recorded in Achnagart, Highlands, on 25 May, beating the previous record of 29 °C set in 1992 at Edinburgh’s Royal Botanic Garden.

In all, it has been the longest warm spell in May since 1992.

This means that, as we draw near to the end of the month, the figures for May now look very different and spectacularly average.

Mean temperature for 1 to 28 May is 10.1 °C, just 0.1 °C above the long-term average. Sunshine is at 104% of the average with 192 hours, so a little above what we would expect, and rainfall is just below at 90% of the average, or 59.8mm.

Clearly these are early month figures and the statistics at the end of the month will change somewhat.

However, the story of this May so far illustrates perfectly just how variable the Great British weather can be. From being a very cold first half of the month, to record breaking temperatures in the second – even if statistically we have had an ‘average’ month, it has actually been a very interesting few weeks of weather.

You can see full summaires of the UK’s weather for every month going back to 2001 on the UK climate pages on our website. The full summary for May will be available a few days after the month has finished.





How often does it snow in May?

15 05 2012

Reports of snow showers in parts of the UK over the past 24 hours and the prospect of more on high ground tonight may seem a little out of context at this time of year, but is it unusual?

Snowfall at this time of year isn’t an annual event, so it’s not completely normal, but it’s fair to say it’s not completely unusual either. We last saw snow in May all the way back in… 2011, just last year, and we also saw more snow in 2010.

If we look back through the records dating back to 1910, the snowiest May on record was most likely in 1979 when 342 weather observation sites reported snow on 2 May.

This snowy spell lasted through the whole of the first week of that month. The light snow showers we’ve seen this May seem slight in comparison.

Besides these wintry showers, much has been made in the media of the ‘cold spell’ which is ‘gripping’ the UK this month and the rather unsettled weather we’ve had.

While many people associate May with the start of summer weather, it can actually be a month of very mixed and variable conditions – with wide contrasts possible.

This is borne out by the piece of old weather lore:

 

Ne’er cast a clout,

Until May is out.

 

While this rhyme is a bit ambiguous and open to interpretation, one view is that this means don’t throw out your winter clothing (from clout – which means thread or cloth) until May is over – presumably because you can expect virtually any type of weather at this time of year.

So, unsettled and cool weather – even with snow or frosts – isn’t out of context in May despite perceptions that it’s typically a warm and sunny time of year.

This week really sums that up. We are expecting some night-time minimums which are below average – isolated areas in Scotland and northern England could get down to freezing or just below.

During the day, however, temperatures in places could get to 15C or above in parts of southern England – and it may even feel quite warm when the Sun is out, particularly in spots sheltered from the wind.

There will also be some rainfall this week, but many places will see sunny and dry spells too.

So, don’t throw away your summer wear yet – nor your winter woolies.

 





Why does it always rain on the UK?

9 05 2012

After the wettest April in records dating back to 1910 and an unsettled start to May, parts of the UK are set to see more heavy rain today and tomorrow.

With all the wet weather, many people have been asking what is to blame and whether something unusual is going on.

In an earlier article on this blog we looked at how the jet stream has influenced the recent spell of unsettled weather, but stressed it is not the only factor at play.

While the jet stream may be an influence, there is nothing unusual about its current position and it regularly behaves in this way.

With that in mind, it’s possible to go a step further and say there is nothing unusual about the UK’s weather over the last few weeks.

That may sound odd on the back of a record-breaking wet month, but we do expect to see records broken and they do topple fairly regularly for one area or another.

The past April fits into this expectation – it was exceptionally wet, but only slightly wetter than the previous record set just a few years ago in 2000 and there are several years close behind.

We only have to look back another month to see that March was the joint warmest on record for Scotland. Looking further back, parts of the UK have seen some of their driest months on record in the last year or so, and we saw the coldest UK December on record in 2010.

The mixture of record-breaking months in recent history illustrates what’s called natural variability – which is a way of summing up the inherent random or chaotic nature of weather. This is why our weather is different from one week, month or year to the next.

Here in the UK that variability is particularly noticeable because of our location. We sit in the mid-latitudes where cold air from the poles meets warm air from the tropics, and have the Atlantic on one side and the large landmass of continental Europe on the other.

All these factors mean our weather can be highly variable and we can see periods of unsettled, wet and windy weather at any time of year – a challenge that the Met Office has to rise to every day to provide the accurate weather forecasts that you, businesses and our government partners have come to expect.








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