May 2014

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

Mean daily maximum: 14.9
Difference from average: +0.6

Mean daily minimum: 7.7
Difference from average: +2.1

Mean air temperature: 11.3
Difference from average: +1.4

Absolute maximum: 21.7 (18th)

Absolute minimum: -1.3 (3rd)

Mean grass minimum: 6.2

Absolute grass minimum: -4.4 (3rd)

Number of ground frosts: 2

Number of air frosts: 1

Mean soil temperature at 30cm depth: 13.2

Mean soil temperature at 100cm depth: 11.3

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

Total for the month: 88.2
Difference from average: +36.0

Percentage of the average: 169%

Wettest day: 13.4 (29th)

Number of rain days (>0.25mm): 18

Number of wet days (=> 1mm): 16

3-month total rainfall to 31st May: 167.2
Difference from average: -4.8

6-month rainfall total to 31st May: 361.8
Difference from average: 15.6

12-month rainfall total to 31st May: 762.8
Difference from average: 113.8

Humidity
(averages for 09:00 hours GMT)

Relative Humidity: 81%

Sunshine
(all averages 1961 – 1990)

Total for the month: 123.9 hours
Difference from average: -44.6

Percentage of the average: 74%

Mean daily sunshine: 4.0 hours
Difference from average: -1.4

Sunniest day: 11.6 hours (18th)

Number of days with no recorded sunshine: 2

Cumulative total sunshine since 1st January: 516.8 hours
Difference from average: -9.5

ISSN1350-483

Comments on May 2014
This was only the warmest May since 2011 but it was nevertheless considerably (more than 1°C) warmer than 2012 or 2013. This was the equal 19th warmest May at Durham since 1850.

Of particular note, May had the highest mean minimum since 2003, which it equals – these two years have the highest mean minimum for May at Durham since records began in 1900.

The 12-month running mean is above 10°C for the first time since March 2012; this is the 15th highest value since 1850 (n=1962) so we are once again in a very warm period as far as the entire climatic record for Durham is concerned.

May was a wet month, well above average. It was also a dull month with only three quarters the normal number of hours of bright sunshine.

Professor Tim Burt
Department of Geography
Durham University