The number of hours of bright sunshine is controlled by the length of day and by cloudiness. The day is shortest in December and longest in June and so in general December is the dullest month and May, June or July the sunniest.
Sunshine duration decreases with increasing altitude, increasing latitude and distance from the coast. Industrial pollution and smoke haze can also reduce sunshine amounts but, because of the Clean Air Act of 1956 and a decline in heavy industry, there has been an increase in sunshine duration over the industrial areas of the north-east.
Overall, coastal sites are the sunniest because of the tendency for convective cloud to develop over inland areas in summer. However, day to day, changes can occur with wind direction and easterly weather often brings dull conditions to coastal districts, especially in spring and early summer when sea fog (known locally as 'fret') occurs.
Average annual sunshine durations over NE England range from almost 1500 hours on the coast to less than 1250 hours in the higher Pennines. These figures compare with values of less than 1100 hours a year in the Shetland Islands to over 1750 hours along the south coast of England and over 1900 hours in the Channel Islands.
The graphs show the average monthly sunshine totals for Sheffield and Morpeth Cockle Park, together with the highest and lowest totals recorded in the stated periods.
The highest known monthly sunshine totals in the region are 313.9 hours at High Mowthorpe in July 2006 and 308.3 hours at Catterick, N Yorkshire in June 1940. The highest UK monthly total is 383.9 hours at Eastbourne in July 1911. In the dullest winter months, less than 20 hours have been recorded - with only 3.6 hours at Morpeth in January 1901.
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