Rainfall in Ireland
Most
of the eastern half of the country gets between 750 and 1000 (mm) of rainfall
in the year. Rainfall in the west generally averages between 1000 and 1400 mm.
In many mountainous districts rainfall exceeds 2000mm per year. The wettest
months, in almost all areas are December and January. April is the driest month
generally across the country. However, in many southern parts, June is the
driest. Hail and snow contribute relatively little to the precipitation
measured.
How often does it rain?
The
general impression is that it rains quite a lot of the time in Ireland , but
two out of three hourly observations will not report any measurable rainfall.
The average number of wet days (days 1mm or more of rain) ranges from about 150
days a year along the east and south east coasts, to about 225 days a year in
parts of the west.
How heavy is the rain?
Unlike
the rain in many other countries, especially in the tropics, average hourly
rainfall amounts in Ireland are quite low, ranging from 1 to 2mm. Short-term
rates can of course be much higher: for example, an hourly total of 10mm is not
uncommon and totals of 15 to 20mm in an hour may be expected to occur once in 5
years. Hourly totals exceeding 25mm are rare in this country and when they do
occur they are usually associated with heavy thunderstorms.
Information
on the frequency of heavy rainfalls is often required by engineers, architects
and others, usually in connection with design criteria for water management or
drainage schemes. A depth duration frequency model allows for the estimation of
point rainfall frequencies for a range of durations for any location in Ireland .
Link to the Met Éireann information on rainfall click here.