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graphs CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE
MONTHLY SUMMARY
No. 597 For SEPTEMBER 2005
A VERY WARM MONTH; FAIRLY SUNNY AND DRY BUT UNSETTLED TOWARDS THE END
Text Box: High pressure lay close to southern Britain for much of the month, although the focus of anticyclonic activity moved to eastern Europe during the third and fourth weeks allowing a changeable southwesterly type to become established over the UK. Mean sea-level pressure ranged from 1mbar below normal in Shetland to 2mbar above in eastern England, with a weak south to southwesterly anomalous flow covering the country.

A cold front crossed the UK on the 1st but a large anticyclone developed the next day, subsequently drifting towards the Baltic and allowing thundery troughs to cross Britain on the 4th/5th. A cut-off depression in the Southwest Approaches controlled the weather from the 8th-11th but pressure rose sharply again on the 12th.

The period 1st-10th gave England and Wales its warmest start to September since 1949. Maxima of 24-26C were reported widely; the high of 29.7C at Northolt (London) on the 4th was the highest for this month in the UK since 1999, while the maximum of 27.4C at Charterhall (Berwickshire) was the highest in Scotland since 1991. The night of the 3rd/4th was widely the warmest in September since 1949, the temperature falling no lower than 20.4C at Guernsey airport and 19.5C at Pembrey Sands (Carmarthen). There were some thunderstorms on the 4th and 5th, but prolonged heavy rain affected southern Scotland and northern England on the 8th-9th, and thunderstorms broke out widely further south on the 9th and 10th, with an unofficial report of 70mm at Danbury (Essex). Although it remained warm in the extreme Southeast, most districts became cooler on the 9th and 10th, and in Scotland it was much colder: Kinbrace (Sutherland) recorded a minimum of -3.5C on the morning of the 9th, the lowest anywhere in the UK so early in the season since 1986, while the max that day at Salsburgh (Lanarkshire) was just 9.8C. Most regions became fine again briefly around the 11th-12th.
Text Box: From the 13th-24th a changeable westerly type affected most of the UK, although high pressure was never far from southern districts. There was a short-lived northerly incursion around the 16th.  During the last week the European high retreated, and a vigorous southwest to westerly type dominated.

A deep depression, formerly hurricane Maria, delivered prolonged heavy rain to the north and west of Scotland  on the 12th-13th, Broadford (Skye) collecting 131mm and Aultbea (Wester Ross) 85mm in 48h. Widespread rain on the 14th-15th was followed by a brief northerly outbreak with a maximum of  9.3C at Lerwick (Shetland) on the 16th and air frost as far south as the Thames Valley on the morning of the 17th. Shap (Cumbria) recorded -1.7C. From 19th-24th all parts of the UK had changeable weather, but further heavy falls of rain in the highlands and islands contrasted with very small amounts in southern England. There was another frost early on the 24th. The remainder of the month was very unsettled with frequent rain in all areas; a vigorous cold front on the afternoon of the 28th triggered tornados in County Antrim (two), and Lancashire. A brief tropical-maritime incursion led to a warm and muggy day on the 30th with highs of 20-22C.

Mean temperature was 1 to 2 degC above the long-term average in all regions, and it was generally the warmest September since 1999 and, as measured by the CET, the fifth warmest in the last 100 years - only those of 1929, 1949, 1961 and 1999 were warmer. In spite of the very unsettled last week, rainfall was below normal, except in parts of northern and western Scotland, northeast England and East Anglia. Monthly totals below 25mm were reported from Royal Deeside, and from Wiltshire and Dorset. There was a small sunshine deficit in the north and west of Scotland and in Northern Ireland; elsewhere sunshine aggregates were 10-20 per cent above normal, and over 30 per cent above in the southwest Midlands.
                                                                                                                                           
    TEMPERATURE   SUNSHINE   RAINFALL        
                                                                                                                                 
                                                                                                                                   
                                  Highest and lowest totals             Highest and lowest totals        
                                  on record for month    
Maximum fall in 24 hrs
   (beginning 09 h)
        on record for month    
Days with snow or sleet
 
Days with fog
(Vis <220 yards at 09 h)
 
                                                                                         
     
Difference from average
   
Difference from average
 
Highest maximum
   
Lowest minimum
   
No. of days with grass
  minimum below 0C
   
Days of no sunshine
 
Maximum duration
       
First year of record
         
Days of no rainfall
 (0.1 mm or less)
         
First year of record
         
Days with thunder
     
  PLACE  
Mean Maximum
   
Mean minimum
             
No. of air frosts
       
Total for month
                   
Total for month
                   
                               
% of average
                   
% of average
                 
                                                                     
                                   
Highest
   
Lowest
 
Year
             
Highest
   
Lowest
 
Year
       
             
Date
   
Date
         
Date
         
Year
         
Date
         
Year
           
                                                                     
    C     C     C     C           Hrs     Hrs       Hrs     Hrs       mm     mm       mm     mm          
                                                                                                                                           
  *Hampstead   20.7   +2.6   12.1   +1.8   28.1   04   04.8   17   00   00   02   09.0   08   135   103   1910   224   1959   072   1945   16   15.5   09   066   107   1910   157   1918   02   1959   03   00   00  
  Thorney Island   20.2   +1.0   12.6   +1.6   26.4   04   05.1   17   00   00   01   12.1   02   191   112   1958   245   1959   129   1967   13   19.2   04   047   089   1941   159   1974   02   1971   02   00   00  
  *Coltishall   20.3   +2.4   11.6   +1.3   26.1   06   06.8   17   00   00   03   11.5   04   161   111   1979   220   2003   082   2001   17   18.2   15   039   074   1964   154   1994   08   1969   02   00   00  
  *Wittering   19.7   +2.0   11.3   +1.6   27.8   04   03.0   24   00   00   05   12.0   02   180   130   1950   207   1964   093   1967   19   14.0   15   054   115   1948   132   1992   02   1959   03   00   00  
                                                                     
  Lyneham   19.9   +2.4   11.0   +1.4   28.1   04   02.7   17   01   00   01   12.3   02   169   119   1952   235   1959   100   1983   14   08.4   28   043   066   1945   142   1974   05   1959   02   00   00  
  Ross-on-Wye   20.5   +2.6   11.1   +1.4   28.0   04   03.0   17   00   00   01   10.3   02   175   137   1914   205   1929   069   1945   17   43.8   10   068   107   1859   203   1976   02   1865   02   00   00  
  *St Athan   19.2   +1.8   12.5   +1.8   25.2   03   04.7   17   00   00   03   12.5   02   150   104   1954   249   1959   074   1956   14   13.4   14   078   087   1954   223   1974   14   1959   01   00   00  
  St Mawgan   18.2   +1.1   12.8   +1.4   23.4   03   06.6   17   00   00   03   12.8   02   167   106   1945   258   1959   080   1956   13   17.8   09   076   094   1944   179   1974   10   1959   00   00   00  
                                                                     
  *Edgbaston   19.4   +2.7   11.7   +1.9   26.9   04   05.5   24   00   00   00   09.9   02   156   123   1887   216   1895   067   1909   16   17.2   10   053   081   1887   165   1918   04   1959   03   00   00  
  *Valley   17.8   +1.0   12.8   +1.6   28.2   04   04.4   24   00   00   04   12.5   06   144   103   1946   214   1949   096   1948   14   08.4   28   053   064   1941   174   1950   03   1986   00   00   00  
  *Woodford   18.5   +1.7   10.3   +1.1   25.6   04   00.4   17   02   00   03   11.3   04   124   101   1945   197   1959   069   1948   09   17.6   29   081   109   1942   171   1965   05   1959   01   00   00  
  *Watnall   19.1   +1.4   11.2   +1.5   27.4   04   04.9   24   00   00   04   12.4   02   145   105   1948   177   1991   075   1993   15   11.0   15   048   103   1942   147   1957   02   1959   02   00   00  
                                                                     
  *Leeming   18.8   +1.5   09.9   +0.7   25.1   06   00.2   24   02   00   03   11.5   02   157   132   1945   200   1986   073   1976   17   20.2   08   054   109   1945   174   1976   04   1959   02   00   00  
  *Boulmer   17.5   +1.2   09.9   +0.6   23.9   06   03.9   24   00   00   02   10.8   12   137   109   1945   205   1986   075   2001   13   46.2   09   076   139   1945   147   1965   12   2004   00   00   00  
  Eskdalemuir   15.7   +0.8   08.6   +1.5   25.5   04   -00.8   24   02   02   06   10.5   01   114   117   1911   153   1959   055   1980   09   29.8   26   135   095   1911   308   1950   18   1972   00   00   00  
  *Bishopton   16.6   +0.3   10.1   +1.4   26.4   04   03.0   24   00   00   07   10.3   04   092   083   1921   169   1996   068   1965   09   29.4   26   119   125   1921   258   1985   11   1972   00   00   00  
                                                                     
  Leuchars   17.8   +1.6   09.5   +0.8   23.5   06   03.6   24   00   00   02   10.0   12   131   104   1922   181   1997   077   1956   12   04.2   26   023   045   1922   149   1950   05   1972   00   00   00  
  Dyce   17.0   +1.5   09.6   +1.6   24.3   06   03.0   24   00   00   03   11.1   04   121   105   1941   181   2004   070   1968   15   08.0   29   032   049   1941   234   1995   15   1959   00   00   00  
  *Stornoway   14.8   +0.6   09.7   +1.0   21.7   04   04.1   09   00   00   04   12.1   09   082   077   1880   175   1903   070   1965   07   34.6   13   165   160   1943   206   1981   34   1968   00   00   00  
  *Aldergrove   16.9   +0.8   10.6   +1.2   22.5   04   01.0   24   01   00   04   09.3   11   096   090   1927   177   1986   070   1962   09   08.8   29   067   083   1927   163   1981   06   1986   00   00   00  
                                                                     
                                                                                                                                           
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative. Thorney Island's      
  sunshine figures are made at a nearby site.