Sunshine and Solar Radiation Ireland normally gets between 1100
and 1600 hours of sunshine each year. The sunniest months are
May and June. During these months, sunshine duration averages
between 5 and 6.5 hours per day over most of the country. The
extreme southeast gets most sunshine, averaging over 7 hours a
day in early summer. December is the dullest month, with an
average daily sunshine ranging from about 1 hour in the north to
almost 2 hours in the extreme southeast. Over the year as a
whole, most areas get an average of between 3 1/4 and 3 3/4
hours of sunshine each day. 1887 was the sunniest summer in the
100 years from 1881 to 1980, according to measurements made at
the Phoenix Park in Dublin. A more recent summer, 1980, was the
dullest. The tendency for coastal regions to record more bright
sunshine than inland areas is the result of the convective
development of clouds over land. This daily development of cloud
is due to the vertical air currents as a result of thermal
heating of the ground. Uplan