Nearly 10 years ago, on 31 July 2008, a stationary band of heavy rain moved across Munster during the evening bringing more than 40mm at several stations. Stations south of the Shannon Estuary had totals exceeding 60mm. Limerick was among the worst areas affected by the heavy rainfall. Castlemahon in the county had a 24-hour daily rainfall of 90.1mm measured at 09:00 UTC on August 1st (see other Limerick stations' rainfall totals in the table below). This accounts for about 10% of the station's normal rainfall for an entire year. The large majority of this rain fell within 7 hours including an estimate of 84.7mm during the period. Such exceptional rainfall in a period like 7 hours has a return period exceeding at least 250 years. Rain from preceding days led soils to be close to saturation and consequently, there was no capacity in the soil to absorb excessive amounts of rainfall. As a result of this unprecedented rainfall, the River Arra in Newcastle West overflowed its banks leaving many houses and businesses severely flooded.
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