January 2009

Temperatures
(all temperatures in degrees Celsius; all averages 1961 – 1990)

Mean daily maximum: 5.9
Difference from average: +0.1

Mean daily minimum: 0.8
Difference from average: +0.6

Mean air temperature: 3.4
Difference from average: +0.4

Absolute maximum: 10.8 (12th)

Absolute minimum: -5.8 (6th)

Mean grass minimum: -2.6

Absolute grass minimum: -11.8 (6th)

Number of ground frosts: 24

Number of air frosts: 7

Mean soil temperature at 30cm depth: 4.0

Mean soil temperature at 100cm depth: 6.1

Rainfall
(all totals in millimetres; all averages 1961 – 1990)

Total for the month: 39.4
Difference from average: -19.6

Percentage of the average: 67%

Wettest day: 6.6 (25th)

Number of rain days (>0.25mm): 16

Number of wet days (=> 1mm): 14

3-month total rainfall to 31st January: 137.2
Difference from average: -41.3

6-month rainfall total to 31st January: 394.9
Difference from average: +41.2

12-month rainfall total to 31st January: 747.3
Difference from average: +98.3

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 87%

Sunshine
(all averages 1961 – 1990)

Total for the month: 80.1 hours
Difference from average: +26.3

Percentage of the average: 149%

Mean daily sunshine: 2.6 hours
Difference from average: +0.9

Sunniest day: 7.0 hours (8th)

Number of days with no recorded sunshine: 3

Wind

The mean wind speed: 12.6km/h [6.8kt]
Difference from average: -2.4km/hr

The highest gust: 73.7km/h [39.8kt] from 187° on 20th

ISSN1350-483

Comments on January 2009
This was the coolest January since 2001 but above average nevertheless, despite feeling much worse! There was the lowest absolute maximum (10.8°C) since 2001 and the lowest absolute minimum (-5.8°C) since 2004. There was the largest number of ground frosts since 1998. The 12-month average is now down to 9.08°C, the lowest since the 2-month period ending September 2001.

It was drier than normal, although both 2005 and 2006 were drier than this January. It was sunnier than normal but only the sunniest January since 2007.

Professor Tim Burt
Department of Geography
Durham University