No heat wave just sunshine and showers this weekend

21 08 2013

You may have seen more headlines in the newspapers today talking about a heat wave heading our way for the weekend. Once again these stories seem a little over-hyped.

The Met Office forecast for the rest of the week does, indeed, show rising temperatures, peaking in the high 20’s Celsius in south-east England on Friday. Temperatures are then expected to return to around average during the course of the weekend, so not a heat wave.

The weather is expected to turn more unsettled from the west during Friday and Saturday, with the risk of some heavy, showery rain around. The rest of the weekend should see some good dry and sunny spells of weather at times, but the risk of occasional showers remains and there is some uncertainty about which areas will see the showers and when.

The uncertainty this weekend comes from complex weather patterns developing over the Atlantic and these will ultimately determine where the showers will be from day to day. For those who like technical speak, it’s called a trough disruption and forecasting this phenomenon continues to be a major challenge to both computer models and humans alike.

So the best thing to do is keep up to date with the forecast to get the latest on how things are expected to develop over this weekend.





July finishes in top three sunniest and warmest

2 08 2013

Met Office figures show that, with a mean temperature of 17 °C, July 2013 was the third warmest in the national record going back to 1910, behind 2006 (17.8 °C) and 1983 (17.3 °C).

This July’s heatwave was more notable for its duration than its intensity, although it is not particularly unusual in a historical context. The last year in which 30 °C was not recorded at any station was in 1993. However, this July stands out in contrast to the run of unsettled summers from 2007 to 2012, and was the most significant UK heatwave since July 2006.

Through the month we saw high pressure sitting over the UK bringing a prolonged period of high temperatures between Saturday 6 July and Thursday 24 July, when a maximum of 28 °C was recorded at one or more locations on each of those 19 days.

The last time the UK saw such a long period of hot weather was August 1997 which also had a 19- day run of high temperatures. The highest temperature for July 2013 was recorded jointly at Heathrow and Northolt on 22 July (33.5 °C). (Although this high temperature has already been surpassed in August, with 34.1 °C recorded at Heathrow on 1 August.

July 2006 still stands as the hottest month on record in the UK with a mean temperature of 17.8 °C and also saw the record July temperature of 36.5 °C at Wisley (19 July 2006).

The heatwave broke on 22 July with thunder and some very heavy downpours. The wettest day in July was in Cumbria, when 79.8mm of rain fell at Carlisle on 28 July (97.4 mm on a 48 hour rainfall total between 0900 GMT 27 July to GMT 29 July 2013).

Looking at the individual countries, the hottest day in Scotland was on 20 July (30.5 °C) at Glenlee, with Castlederg in Northern Ireland and Porthmadog in Wales recording their highest temperatures on 19 July (30.1 °C and 31.4 °C respectively). England’s hottest day was also the aforementioned UK’s hottest day (33.5 °C on 22 July Heathrow and Northolt).

July’s UK rainfall total was 64mm, with Scotland receiving near normal levels at 83.1 mm and the whole of England drier than average at 52.3 mm (but with Northern England registering above average rainfall with 75.8 mm and Southern England below average at 39.8 mm). Wales (58.0 mm) and Northern Ireland (78.2 mm) were slightly drier than average.

Statistics:

Mean Temperature Sunshine hours Rainfall  
July Actual Diff from Avg Actual % of Avg Actual % of Avg
  degC degC hours % mm %
UK 17.0 1.9 250.7 145 64.1 82
England 18.1 1.8 274.1 142 52.3 83
Wales 17.2 2.0 288.9 161 58.0 63
Scotland 15.2 1.9 205.8 146 83.1 84
N Ireland 17.0 2.4 227.3 162 78.2 96




Warm air to bring short hot spell

31 07 2013

Temperatures are forecast to exceed 30 °C tomorrow in some areas with a heat health warning in place for parts of the south east. However, these high temperatures are expected to be short lived with temperatures dropping by a few degrees again over the weekend.

maximum-temperatures

Why are we only seeing one day of high temperatures?

The brief warmer weather is due to hot air being drawn north from the Spanish plateau to the British Isles. Shortly after, Atlantic air coming in from the west brings a return to average conditions for the time of year.

The surface pressure charts below show the warm air being drawn up, followed by the cold front moving in from the west.

surfacepressurechart

Watch our video for help understanding synoptic charts.





July starts dry, sunny and warm

17 07 2013

Early Met Office figures for the first half of July show that it has been warmer, drier and sunnier than usual so far this month.

We’ve now had 11 days with temperatures over 28 °C somewhere in the UK, making it the longest hot spell since 2006.

The UK mean temperature up to the 15th July is 16.1 °C, a degree above the long term average for the whole of the month. The days have been particularly warm so far, with the average maximum temperature for the UK being 21.3 °C, 2 degrees above normal.

Rainfall for the UK from 1-15 July was 9.2 mm. At this stage we would expect to have seen about 48 % of the full month average, however we have only seen 12 %. We have seen less than 5 mm widely across much of England and parts of eastern Scotland (many locations with only 1 or 2 mm).

Up to the 15th we have seen 132 hours of sunshine across the UK, which is 77 % of the full month average. Again, we would have expected to have seen about 48% at this point in an ‘average’ month.

Looking at the individual countries, Scotland’s mean temperature has been 14.4 °C (1.2 °C above average) and Northern Ireland’s has been 16.3 °C (1.7 °C above average). England’s has been 17.0 °C (0.7 °C above average), and Wales’ has been 16.3 °C (1.1 °C above average).

Wales had the most sunshine with 155 hours, which is 86 % of the full-month long-term average.

England has seen the least rainfall for the first half of the month with 4.0 mm, just 6 % of the long term July average. Scotland has seen the most rain with 16.8 mm, but even that is only 17 % of the full-month average.

To put this in context, the driest July on record across the UK was in 1955 when there was 30.6 mm of rain. With only 9 mm of rain so far in the UK this July, this is likely to be a very dry month but – with two weeks to go – it’s too early to say where it will end up in the national series dating back to 1910.

For the longer running England and Wales precipitation record which dates back to 1766, the record driest July was in 1825 with just 8 mm of rain. England and Wales have seen just 4 mm so far this month, but – again – it’s too early to judge where it will end up in the records.

With regards to sunshine hours, 1955 is the sunniest July on record with 256 hours of sunshine, with 2006 close behind with 253 hours.

The warmest July on record is 2006 with a UK mean temperature of 17.8 °C; this is also the warmest month in the national record which goes back to 1910.

Mean Temperature Sunshine hours Rainfall  
1-15 July Actual Diff from Avg Actual % of Avg Actual % of Avg
  degC degC hours % mm %
UK 16.1 1 132.1 77 9.2 12
England 17 0.7 147.2 76 4 6
Wales 16.3 1.1 154.7 86 8.7 9
Scotland 14.4 1.2 104.1 74 16.8 17
N Ireland 16.3 1.7 114 81 15.7 19

The reason behind this very warm weather is an area of high pressure which has been sitting right above the UK since the start of the month.

This dry weather is in sharp contrast to last year’s wet weather and follows on from a dry June this year.

The Environment Agency measures water resources in England every week to assess how dry the soils are and how much rain they can soak up, the amount of water flowing in rivers, stored below ground in aquifers and above ground in reservoirs, and the outlook for the coming months.

Trevor Bishop, head of water resources at the Environment Agency, said: “Last year’s exceptionally wet summer and autumn has left us in a fairly good water resources position, with most rivers, reservoirs and underground water stores around normal for the time of year. Some river levels are dropping as a result of the hot, dry spell that we are enjoying, and we would urge everyone to continue use water wisely, to protect water supplies and the environment.”

More information can be found in their latest water situation report.





First ‘Heat-Health’ alert of the summer

12 07 2013

Parts of England have been put on Heat-Health alert as the hot temperatures continue into the weekend.

sunshine

Temperatures are expected to climb close to heatwave thresholds across the East Midlands and Yorkshire and the Humber regions during Friday and Saturday, with highs of 29°C expected. The highest temperatures transfer southwards to affect East of England, Southeast England, London and parts of Southwest England during Saturday and Sunday. Saturday will see the hottest day of the year with temperatures reaching the low 30s in the south east.

The Heat-Health Watch system operates in England from 1 June to 15 September each year in association with the Department of Health.

The Heat-Health Watch system comprises four levels of response based upon threshold maximum daytime and minimum night-time temperatures. These thresholds vary by region, but an average threshold temperature is 30 °C by day and 15 °C overnight.

A Level 2 alert is triggered as soon as the risk is 60% or above for threshold temperatures being reached in one or more regions on at least two consecutive days and the intervening night. This is an important stage for social and healthcare services who will be working to ensure readiness and swift action to reduce harm from a potential heatwave.

Local authorities, professionals and community groups can prepare for hot weather by reviewing the Heatwave Plan on the PHE website.

Dr Angie Bone, Heatwave Plan lead for PHE, said: “While many people enjoy hot weather, high temperatures can be dangerous, especially for people who may be particularly vulnerable such as older people, young children and those with serious illnesses.

“The Heatwave Plan is an important component of overall emergency planning and sets out a series of clear actions that can be taken by healthcare organisations, local authorities, professionals working with vulnerable people, and individuals to help keep people safe during extreme heat.
“Everyone can enjoy the sun safely by keeping out of the heat at the hottest time of the day, avoiding sunburn and staying hydrated with plenty of cool drinks. The elderly and those with long-term illnesses are particularly vulnerable to the effects of very hot weather, so it’s important to look out for them and keep indoor areas as cool as possible.”

Visit gov.uk for more information on the PHE Heatwave Plan.

For tips on staying safe in the sun, visit our Great British Summer web pages.





What is a heat wave?

4 07 2013

This weekend and into next week temperatures are expected to reach the high twenties Celsius in southern England. This is certainly warmer than we would expect at this time of year – the average maximum temperature for July in England is 20.9 °C – but does it constitute a heat wave?

How hot is a heat wave?

There’s actually no official definition of a heat wave in the UK. In America, where high temperatures are more likely, the official classification is based on the Heat Index. The Heat Index temperature is a ‘feels-like’ temperature calculated by combining the temperature and relative humidity.

Depending on the local climate, an excessive heat warning is issued when the Heat Index is expected to exceed 105 °- 110 °F (40 °C – 43 °C) for at least two consecutive days.

Australia also has variable definitions depending on the state. In Adelaide, a heat wave is defined as five consecutive days at or above 35 °C, or three consecutive days at or over 40 °C.

Heat health watch

Working in association with the Department of Health, the Met Office provides a heat health warning system for England.

The Heat-health watch system comprises four levels of response based upon threshold maximum daytime and minimum night-time temperatures. These thresholds vary by region, but an average threshold temperature is 30 °C by day and 15 °C overnight for at least two consecutive days.

When was the last time we had a prolonged spell of hot weather in the UK?

The last time we saw a long spell of warm weather was in July 2006, where temperatures were above 28 °C in many areas for a fortnight. We have had shorter spells of warm weather since, however, such as the 23 – 26 July last year, when temperatures peaked at 30.7 °C.

How hot will it get this weekend?

You can see the expected maximum temperature range for your area on our website. Temperatures are not currently expected to exceed the heat health watch threshold, but keep up to date with warnings on our website.

temprangelondon

Visit our summer pages for activity ideas for hot and sunny weather.

http://www.youtube.com/watch?v=GrBuD9eAmsk





Met Office in the News: “Tropical Storms to hit Wimbledon”?

26 06 2012

There have been several articles in the Daily Express over the last couple of days reporting ‘Summer is on the way at last’ with temperatures set to reach 34 Celsius this week and ‘Tropical storms set for Wimbledon’.

These headlines are unfortunately wide of the mark and rather misleading, both by implying that hot and sunny weather is on the way and that Wimbledon will be hit by tropical storms.

Although the Met Office has spoken to the Daily Express, the forecasts featured in the stories have not come from the Met Office, but from an independent forecaster.

The Met Office forecast for this week is for a couple of days of warm, humid and rather cloudy weather across much of the UK, with temperatures reaching 26 or 27 Celsius in any sunshine. For more detail you can find the latest weather forecast on our website.

It is our understanding that the temperatures of 34 deg C referenced in the articles are actually feels like temperatures taken from the website of an independent forecaster rather than actual air temperature. This is not made clear within the article and is potentially misleading.

The inference – through the lack of reference to the original source of the forecasts – that these forecasts have come from the Met Office is very misleading for the public, and potentially damages the reputation not only of the Met Office, but the wider weather forecasting community.

The Met Office is a world leader in meteorological science and our forecasts are recognised the world over as some of the best in the world. We are proud to be trusted to give the best possible guidance on the weather by the public and we report the weather exactly as it is.





Met Office in the Media: 14 October 2011

14 10 2011

There has been some stories in the media today about some fine weather expected over the coming weekend.  Some of these stories have suggested that we are going to see a heatwave or even that October will be warmer than summer.  This is simply not the case

  • T-shirt time! Freak heatwave to hit Britain this weekend – as forecasters say this October will be hotter than summer (Daily Mail)
  • Get ready for the last of the summer sun (The Sun)

Most of England and Wales will have a sunny day on Saturday although northwestern areas will be cloudier with rain across parts of Northern Ireland and Scotland. Temperatures will be between 16 to 18 Celsius across the UK, and although rather mild, this is far from a heatwave.  We have already seen temperatures in excess of 20 deg C every day this week and therefore the weekend looks a little cooler than previous days.  

Other reports have also suggested that forecasters are saying October will be warmer than the summer. Again, this is just not the case.  It would be correct to say that we have seen a very mild start to October with the warmest October day ever recorded on 1st October when Gravesend reached 29.9 C.  However this does not compare with the 33.1 Celsius that was recorded on 27 June 2011

We are not even half way through the month and the Met Office have not complied any national weather statistics for the month yet. It is just not possible to compare one month with the three months of Summer, especially when the month is not complete.

Elsewhere, the Economist has reported on the ground-breaking science from the Met Office that identifies a link between solar UV output and cold winters in parts of Europe and North America.





What has brought the warm autumn weather to the UK?

27 09 2011

Over the next few days we are expecting a spell of very warm weather for this time of year across much of England and Wales and even parts of Scotland too. The reason why we are seeing this unseasonable warm spell is due to an area of high pressure which has developed across much of central Europe, centred on Germany and Poland.

This draws up very warm air from a long way south, from parts of France and Spain. That comes across a dry continent removing most of the moisture out of the air. As a result we see very little in the way of cloud with blue skies and plenty of sunshine. As a result the sunshine warms the ground and the ground warms the air so we see high temperatures for this time of the year.

In the video below Paul Gundersen, Met Office Chief Forecaster provides more details about this warm spell, how long it will last and whether this really is an ‘Indian Summer’.





‘Flaming June’ forecasts not from the Met Office

2 06 2011

Several media outlets are reporting that we are likely to see a heatwave in June and in some cases throughout the summer.  Some of the headlines attribute the June forecast to the Met Office.

These forecasts were based on comments from other forecasting organisations, not the Met Office.  At no time has the Met Office said that the whole of June will be hot nor have we issued forecasts for Wimbledon and Glastonbury or a summer forecast.

This weekend (3-5 June) will be warm in many places at first, with top temps in the mid to high 20s. But we do expect it to cool down later and into next week.

The longer term 6-15 day forecast issued on the Met Office website on 1 June for the period up to the middle of June said:

The UK entering the new week rather unsettled with a cooler feel when compared to the first few days of June. Some sunny spells are expected, but also rain or showers, with rainfall most persistent and heaviest towards the north and west, giving slightly below average temperatures here. Meanwhile the southeast may become locally warm, with a risk of heavy or thundery showers, whilst the best of any dry weather more likely in the west. Later in the week, conditions look to remain unsettled, with showers perhaps turning heavy at times with a risk of thunder. It should remain rather cool for many, although again, perhaps warmer towards the southeast. Towards the end of the period, conditions continue rather unsettled with rain or showers, separated by drier and brighter interludes.

Met Office weather forecasts for the next five days, 6 to 15 days ahead and 16 to 30 days ahead are available on the Met Office website.








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