July 2006

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

Mean daily maximum: 24.3
Difference from average: +5.0

Mean daily minimum: 12.4
Difference from average: +2.0

Mean air temperature: 18.4
Difference from average: +3.6

Absolute maximum: 30.5 (17th)

Absolute minimum: 5.3 (14th)

Mean grass minimum: 9.7

Absolute grass minimum: 1.7 (14th)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 18.1

Mean soil temperature at 100cm depth: 15.4

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

Total for the month: 6.6
Difference from average: -44.9

Percentage of the average: 13%

Wettest day: 2.0 (9th)

Number of rain days (>0.25mm): 4

Number of wet days (=> 1mm): 4

3-month total rainfall to 31st July: 117.9
Difference from average: -38

6-month rainfall total to 31st July: 232.7
Difference from average: -63.8

12-month rainfall total to 31st July: 539.2
Difference from average: -109.8

Sunshine
(all averages 1961 – 1990)

Total for the month: 248.3 hours
Difference from average: +93.4

Percentage of the average: 160%

Mean daily sunshine: 8.0 hours
Difference from average: +3.0

Sunniest day: 12.9 hours (14th)

Number of days with no recorded sunshine: 0

Cumulative total sunshine since 1st January: 844.9 hours
Difference from average: +81.2

Wind

The mean wind speed: 10.4km/h [5.6kt]
Difference from average: -1.1km/hr

The highest gust: 53.7km/h [29kt] from 175° at 12:47 GMT on 30th

ISSN1350-483

Comments on July 2006
This was the warmest July on record at Durham since records began in 1850. It beats the previous record (1983) by a massive 0.7°C. The mean maximum (24.3°C) is the highest on record for any month (my records for this only start from 1950), beating the previous record of 23.1°C for August 1995, and is a huge 5.0°C above the mean maximum for July! The absolute maximum saw the temperature in Durham exceed 30°C for the first time since August 1995; indeed only three months have recorded maxima above 30°C since 1962: August 1995 (30.3°C), July 2006 (30.5°C) and August 1990 (32.5°C). Daily temperature exceeded 25°C on 18 days, and only three days had a maximum below 20°C. The mean minimum temperature was less far above average, but still the third highest for July (since 1950) and the fifth highest for any month. Of the air temperature measurements this July, only the absolute minimum was unexceptional.

A rainfall total of 6.6mm for the month seems very low but accords with the Met Office anomaly map which shows the Durham area to be below 25% of the monthly average. Measurable rain was only recorded on four days. This was the second driest July on record at Durham since 1852; only 1878 (4.7mm) has been drier. All long-term measures of accumulated rainfall are now well below average, with the 12-month total to 31st July 2006 more than 100mm below the long-term average.

It was the third sunniest July since 1882 at Durham, beaten only by 1911 and 1955. In addition to these two for July; the July 2006 sunshine total has also been beaten only once in August (1995), once in May (1971) and three times in June (1940, 1949 and 1957); the sunshine total of 297 hours in 1940 remains easily the highest ever recorded at Durham for any month, with July 2006 ranking 8th highest for any month. There was a full 3 hours sunshine above the average each day and the overall total was 60% above the average. It was the first July since 1993 with sunshine recorded every day.

Professor Tim Burt
Department of Geography
Durham University