Monthly Climate Summary for December 2011 at Chesham (Tennis Club)
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                   An unsettled month;  rather cold third week then much milder       back forward
                         
Overall mean temperature was 5.3 ēC which is   degC compared with the 1971-2000 average  
Mean day maximum (09-21) was 8.2 ēC which is   degC compared with the 1971-2000 average  
Mean night minimum (21-09) was 2.4 ēC which is   degC compared with the 1971-2000 average  
Mean 24hr maximum (09-09) was 8.2 ēC                
Mean 24hr minimum (09-09) was 1.4 ēC                
  Highest day max was 11.7 ēC on  the   26            
  Lowest day max was 2.8 ēC on  the 16            
  Highest night min was 10.4 ēC on  the 26            
  Lowest night min was -6.4 ēC on  the 19            
  Lowest grass min was   ēC on  the              
                         
Total rainfall this month was 88.2 mm which is   per  cent of the 1971-2000 average    
  Highest daily fall was 22.9 mm on  the 12            
Number of hours with rain was                    
Equiv. TSR rainfall duration was 26.4 hrs which is   per  cent of the 1971-2000 average    
  Highest no of wet hrs   hrs on  the              
  Highest duration 6.0 hrs on  the 12            
  Mean rainfall intensity 3.34 mm/hr                
                         
Total est sunshine this month was 14.3 hrs which is   per  cent of the 1971-2000 average    
Equiv. C/S sunshine total was   hrs which is   per  cent of the 1971-2000 average    
  Highest daily sun was 1.6 hrs on  the 7            
                         
Maximum  snow depth  was   cm on  the               
                         
Mean sea-level pressure at 09Z 1011.1 mbar which is   mbar compared with the 1961-1990 average  
  Highest pressure at 09Z 1033.6 mbar on  the 27            
  Lowest  pressure at 09Z 984.0 mbar on  the 16            
                         
Total number of days with:                      
Air Frost 9   0.2mm rain 23   No  sun 14   Snow lying 0    
Grnd Frost 0   1.0mm 14   3h  sun 0   Snow/sleet 0    
Max < 0ēC 0   5mm 6   6h  sun 0   Hail 0    
Max > 10 8   10mm 1   9h  sun 0   Thunder 0    
Max > 20 0   25mm 0   12h sun 0   Fog at 09Z 0    
Max > 30 0         15h sun 0   Gale 0    
                         
Notable events during the month: