May and June are the sunniest months in the year. Although the daily amount of sunshine during these months tend to average out at between five and six hours a day, the area in the extreme southeast of the country tends to get the most. This area can get, on average, more than 7 hours of sunshine a day during the early summer.
December is the month that has the least sunshine. During the month of December, northern areas of the country tend to receive an average of 1 hour of sunshine daily. Again, the extreme southeast tends to get the most sunshine and receives an average of almost two hours of sunshine daily. The average for the rest of the country tends to average between 3 ¼ and 3 ¾ hours of sunshine on a daily basis.
The annual total amount of sunshine that Ireland receives, is around 1400-1700 hours. While this may see to be a fair amount of sunshine, the fact is that the sunniest place in the world, the Eastern Sahara Desert, receives an annual average of 4300 hours of sunshine.
Ireland has begun to develop a reputation for being overcast much of the time. This reputation is not totally undeserved since Irish skies are often completely overcast. In fact, they tend to be completely overcast more than 51% of the time.
This is primarily due to Ireland’s position near the path of Atlantic low pressure systems. These low pressure systems moderate the air temperature and give Ireland the precipitation which has led to the nickname “The Emerald Isle”. Phoenix Park in Dublin recorded that 1887 was the sunniest summer in the period lasting from 1881 to 1980. The year 1980 had the dullest summer. In that year, scientists only measured half the amount of the sunshine as was measured in 1887.
How Sunshine is Measured
Met Eireann measures both, the amount and the strength of sunshine using two different methods. The amount of sunshine that the area receives is measured using a Campbell-Stokes sunshine recorder. This unique device uses a crystal sphere. This causes the sunlight to become focused to the point where it can burn a trail on a piece of cardboard which is placed behind the sphere. Solar energy is measured in a different way. It uses a more sophisticated machine called a solarimeter.
The measurements that are taken are used for both agricultural applications and when solar projects are being planned and conducted.