April 2003

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

Mean daily maximum: 14.0
Difference from average: +3.0

Mean daily minimum: 4.3
Difference from average: +1.2

Mean air temperature: 9.2
Difference from average: +2.1

Absolute maximum: 24.1 (17th)

Absolute minimum: -1.1 (8th)

Mean grass minimum: 2.0

Absolute grass minimum: -4.5 (10th)

Number of ground frosts: 10

Number of air frosts: 5

Mean soil temperature at 30cm depth: 9.9

Mean soil temperature at 100cm depth: 9.0

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

Total for the month: 14.8
Difference from average: -33.0

Percentage of the average: 31%

Wettest day: 4.8 (27th)

Number of rain days (>0.25mm): 8

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

3-month total rainfall to 30th April 2003: 35.8
Difference from average: -104.8

6-month rainfall total to 30th April 2003: 270.2
Difference from average: -27.4

12-month rainfall total to 30th April 2003: 656.8
Difference from average: +7.8

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 70.4%

Sunshine
(all averages 1961 – 1990)

Total for the month: 163.1 hours
Difference from average: +29.9

Percentage of the average: 122%

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

Sunniest day: 11.3 hours (16th)

Number of days with no recorded sunshine: 1

Cumulative total sunshine since 1st January: 517.2 hours
Difference from average: 159.3

Wind

The mean wind speed: 13km/h [7kt]
Difference from average: -1.3km/hr

The highest gust: 72.2km/h [39kt] from 205° at 04:14 GMT on 1st

ISSN1350-483

Comments on April 2003
Another remarkably warm, dry and sunny month!

This was the 4th warmest April since 1850 and the warmest since 1987 (1949 holds the record). The 17th was the warmest April day ever recorded at Durham (since 1847), the maximum of 24.1°C beating the previous record of 23.8°C. The mean daily maximum was the warmest since 1950 (when my ledger begins); the mean daily minimum was the highest since 1993.

Rainfall in April 2003 was exactly the same as in 2002, the driest Aprils since 1997. This was the third very dry month in a row, and indeed the three-month total (35.8mm) is the second lowest total for any consecutive three months since 1850, the driest such period being December 1857 – February 1858! The number of rain days (8) was the lowest since 1982. It felt like a downpour on the 27th but in fact the daily total of 4.8mm is very modest (but not that rare as a maximum 24-hour total for April, in fact). It was a little less sunny than April 2002 but otherwise the sunniest since 1995.

I am aware that my post-1950 ledger does not include all necessary records, as more than one reader has commented. I hope to have all records computerised in the near future, which will allow a more accurate assessment of record-breaking events (For example, when was the 23.8°C mentioned above?). Meanwhile I am grateful (again) to Dave O’Hara of Ferryhill for pointing out that 1894 was the sunniest March recorded at Durham with 191 hours, slightly more than the total last month (March 2003 tied with 1907).

Professor Tim Burt
Department of Geography
Durham University