June 2009

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

Mean daily maximum: 18.3
Difference from average: +0.8

Mean daily minimum: 8.6
Difference from average: 0.0

Mean air temperature: 13.5
Difference from average: +0.5

Absolute maximum: 25.6 (22nd)

Absolute minimum: 3.5 (4th)

Mean grass minimum: 7.6

Absolute grass minimum: 1.2 (4th)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 15.5

Mean soil temperature at 100cm depth: 13.6

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

Total for the month: 80.6
Difference from average: +28.8

Percentage of the average: 156%

Wettest day: 10.4 (20th)

Number of rain days (>0.25mm): 19

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

3-month total rainfall to 30th June: 155.6
Difference from average: +4.5

6-month rainfall total to 30th June: 251.7
Difference from average: -51.1

12-month rainfall total to 30th June: 741.2
Difference from average: +92.2

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 84%

Sunshine
(all averages 1961 – 1990)

Total for the month: 131.7 hours
Difference from average: -32

Percentage of the average: 81%

Mean daily sunshine: 4.4 hours
Difference from average: -1.1

Sunniest day: 11.7 hours (1st)

Number of days with no recorded sunshine: 0

Cumulative total sunshine since 1st January: 797.4 hours
Difference from average: +107.3

Wind

The mean wind speed: 7.8km/h [4.2kt]
Difference from average: -3.8km/hr

The highest gust: 59.6km/h [32.2kt] from 260° at 16:10 GMT on 19th

ISSN1350-483

Comments on June 2009
June had the 29th highest mean maximum temperature since 1900 but with the mean minimum being exactly average, mean air temperature was, overall, only a little above average. There was the lowest grass minimum since 1999, but no ground frost within Durham City all month. There were some warm spells: at the beginning of the month, in the middle (Durham Regatta weekend), 22nd – 24th and at the end of the month. In between were some cooler days. The maximum on the 5th of only 8.3°C deserves some mention; we do not compile a list of lowest maximum temperature in each month but if we did, this would surely be close to the record!

Rainfall was well above average, ending a run of 7 months of below-average rainfall. It was wetter than last June, but much less wet than June 2007. Overall, June 2009 ranks 135th wettest in 160 years (since 1850).

It was less sunny than in May. It was sunnier last June but there was less sun in June 2007.

June was a calm month with average wind speed well below average. The maximum gust was only 59.6km/h on the 19th.

Professor Tim Burt
Department of Geography
Durham University