April 2017

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

Mean daily maximum: 12.9
Difference from average: +1.9

Mean daily minimum: 4.1
Difference from average: +1.0

Mean air temperature: 8.5
Difference from average: +1.5

Absolute maximum: 19.7 (9th)

Absolute minimum: -0.8 (18th)

Mean grass minimum: 1.6

Absolute grass minimum: -3.6 (18th)

Mean concrete minimum: 3.5

Absolute concrete minimum: -2.4 (18th)

Number of ground frosts: 8

Number of air frosts: 3

Mean soil temperature at 30cm depth: 10.4

Mean soil temperature at 100cm depth: 9.5

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

Total for the month: 29.0
Difference from average: -18.3

Percentage of the average: 61%

Wettest day: 7.0 (25th)

Number of rain days (>0.25mm): 9

Number of wet days (=> 1mm): 7

3-month total rainfall to 30th April: 152
Difference from average: -20.0

6-month rainfall total to 30th April: 316.6
Difference from average: -29.6

12-month rainfall total to 30th April: 607.1
Difference from average: -41.9

Humidity
(averages for 09:00 hours GMT)

Relative Humidity: 73%

Sunshine
(all averages 1961 – 1990)

Total for the month: 162.5 hours
Difference from average: +29.3

Percentage of the average: 122%

Mean daily sunshine: 5.4 hours
Difference from average: +1.0

Sunniest day: 11.2 hours (8th)

Number of days with no recorded sunshine: 0

Cumulative total sunshine since 1st January: 418.2 hours
Difference from average: +60.4

ISSN1350-483

Comments on April 2017
This was the 20th equal warmest April since 1850; eight of the even warmer Aprils have been since 2000. It was also the 20th equal highest mean maximum and the 17th equal highest mean minimum temperature. There was the warmest April day (9th) since the exceptional April 2011 when four days exceeded 20°C. As widely publicised, April was a dry month, with less than two-thirds of average total at Durham. As expected, it was a sunny month, the 29th sunniest April in Durham since 1881.

Professor Tim Burt
Department of Geography
Durham University