Monthly Climate Summary for December 2009 at Luton (Cranleigh Gardens)
                          home daily
                              Unsettled and mild till the 10th;  very cold and wintry 16th-25th       back forward
                         
Overall mean temperature was 2.8 ēC which is -2.1 degC compared with the 1971-2000 average  
Mean day maximum (09-21) was 4.9 ēC which is -2.2 degC compared with the 1971-2000 average  
Mean night minimum (21-09) was 0.7 ēC which is -2.0 degC compared with the 1971-2000 average  
Mean 24hr maximum (09-09) was 5.4 ēC                
Mean 24hr minimum (09-09) was 0.0 ēC                
  Highest day max was 10.5 ēC on  the   7            
  Lowest day max was -1.0 ēC on  the 19            
  Highest night min was 8.5 ēC on  the 6            
  Lowest night min was -6.8 ēC on  the 19            
  Lowest grass min was -12.7 ēC on  the 20            
                         
Total rainfall this month was 113.9 mm which is 168.2 per  cent of the 1971-2000 average    
  Highest daily fall was 19.8 mm on  the 29            
Number of hours with rain was                    
Equiv. TSR rainfall duration was 109.8 hrs which is 176.5 per  cent of the 1971-2000 average    
  Highest no of wet hrs   hrs on  the              
  Highest duration 15.0 hrs on  the 29            
  Mean rainfall intensity 1.04 mm/hr                
                         
Total CS sunshine this month was 55.8 hrs which is 115.1 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 6.2 hrs on  the 20            
                         
Maximum  snow depth  was 19.0 cm on  the  22            
                         
Mean sea-level pressure at 09Z 1006.8 mbar which is -7.8 mbar compared with the 1961-1990 average  
  Highest pressure at 09Z 1033.6 mbar on  the 11            
  Lowest  pressure at 09Z 985.9 mbar on  the 22            
                         
Number of days with:                      
Air Frost 12   0.2mm rain 22   No  sun 10   Snow lying 10    
Grnd Frost 21   1.0mm 15   3h  sun 7   Snow/sleet 9    
Max < 0ēC 1   5mm 7   6h  sun 2   Hail 0    
Max > 10 3   10mm 5   9h  sun 0   Thunder 0    
Max > 20 0   25mm 0   12h sun 0   Fog at 09Z 6    
Max > 30 0         15h sun 0   Gale 0    
                         
Notable events during the month: