PITSFORD HALL WEATHER STATION
NORTHAMPTON, UNITED KINGDOM

MONTHLY WEATHER REPORT - DECEMBER 2000


Monthly Assessment


The first two weeks of December were very unsettled, albeit rather mild. Low pressure to the 
west brought bands of rain across the county during the first week with further deep depressions 
in the second week. Thunder was heard at Pitsford on the 6th with 16.4mm of rain recorded on a 
very wet day on the 7th. Winds were also strong with gusts of up to 44mph on the 7th and 46mph 
on the 8th. 

A rather cold spell then followed during the third week with daily temperatures falling 
continually until the 18th. Air frosts were recorded from the 15th until the 18th, and ground 
frosts from the 14th until the 18th. A milder spell of weather then followed which brought 
some foggy mornings and overcast conditions from the 19th until the 26th. Some heavy showers 
on the 23rd and 24th. Christmas Eve was particularly wet with 9.1mm falling over a 15.5 hours. 

Although the county missed out on a white Christmas, significant snow fell in the early hours 
of the 28th giving a covering of 8.0cm at Pitsford. With severe overnight frosts (down to -7.4C 
on the 29th) snow lay on the ground for the last few days of the month. The 29th was a 
particularly cold day with air maxima not rising above freezing (-0.4C).

Overall, December's temperatures balanced out at around the long term average (-0.1C) with 
rainfall amounts very slightly above the norm (122.5%).


Climatological Statistics - December 2000

Air Temperatures				
The Highest Maximum: 13.1C on 4th
The Lowest Maximum: -0.4C on 29th
The Highest Minimum: 10.7C on 12th
The Lowest Minimum: -7.4C on 29th

The Mean Maximum: 7.4C
The Mean Minimum: 2.8C  
The Overall Mean: 5.1C  
Difference from the Monthly Mean: -0.1C
				
Relative Humidity:				
Highest Relative Humidity (at 0900): 100% on 17th, 18th, 19th, 21st, 22nd, 28th & 30th
Lowest Relative Humidity (at 0900): 82% on 6th
Mean Relative Humidity (at 0900): 94.6%
    
Dew Point:				
The Highest Dew Point (at 0900): 11.5C on 12th
The Lowest Dew Point (at 0900): -5.9C on 29th
The Mean Dew Point (at 0900): 4.0C
				
Rainfall:				
Total: 74.0mm  
Difference from the Monthly Mean: 122.5% 
Duration: 73.2hrs
Highest 24-hour fall (from 0900): 16.4mm on 7th
Rain Days (>/=0.2mm): 20
Wet Days (>/=1.0mm): 14  
Lowest pH: 6.37 on 18th
			
Sunshine:				
Total Duration of Bright Sunshine: 52.9hrs
Sunniest day: 6.3hrs on 15th
Sunless days: 14
Cloud cover (mean at 0900): 6.4 oktas (80%)
				
Pressure (reduced to sea level):				
The Highest Pressure: 1018.3mb on 21st
The Lowest Pressure: 977.3mb on 8th
Mean Pressure (recorded at 0900): 1005.0mb
		
Winds:				
Run of wind (mean over 24 hrs): 158.4 miles  
Mean daily wind speed: 8.6mph
Highest 24-hour Wind Speed: 17.3 mph on 12th   
Run of wind (to date): 4911.1 miles
Highest Maximum Gust: 56mph on 12th
Highest wind strength (at 0900): 31.1mph on 5th
Mean wind strength (at 0900): 12.3mph
		

		
Winds from the Following Directions:				
N 1, NE 4, E 4, SE 2, S 14, SW 0, W 1, NW 4, Calm 1	
		
				
Ground Temperatures:			 	
Lowest Grass Minimum: -13.6C on 30th
Mean Grass Minimum: -0.2C
Lowest Concrete Minimum: -8.2C on 29th
Mean Concrete Minimum: 1.9C
Lowest Bare Earth Minimum: -9.6C on 29th
Mean Bare Earth Minimum: 1.0C
				
Soil/Earth Temperatures:		 		
5cm mean: 4.6C  
10cm mean: 4.9C  
20cm mean: 5.7C  
30cm mean: 6.3C  
40cm mean: 6.6C  
50cm mean: 7.1C  
100cm mean: 7.7C 
				
Days with:				
Thunder: 1 on 6th  
Hail less than 0.5mm: 1 on 12th  
Hail greater than/equal to 0.5mm: 0   
Snow or snow & rain: 2 on 28th & 31st  
Fog: 7
Air Frost: 9
Duration of Air Frost: 131 hours
Ground Frost: 13   

Evaporation: 

Suspended until next summer.
				
Observations made at 0900 UTC. Averages refer to the
period 1961-1990.