Hydrology bulletin on rainfall, river flows, lake levels, groundwater levels…
Hydrology Summary Bulletin – September 2026
Hydrology bulletin on rainfall, river flows, lake levels, groundwater levels and spring outflows for September 2026
September 2026 was warmer than average across Ireland, particularly in the east. The month was also wetter and duller, with frequent rain and showers. Weather conditions were mainly influenced by low pressure to the north and high pressure to the south, creating a mild Atlantic airflow from the south and west. While brief dry spells occurred when high pressure extended northwards,
periods of heavy rain were brought by active weather fronts moving in from the Atlantic. Heavy rain fell on Sunday 27th in the south and east. A storm passed Ireland well to the west on Tuesday 29th moving north but still brought widespread rain and strong winds along with a very warm tropical maritime airmass.
Compared to August, average river flows increased at 93% of monitoring stations assessed; however, 49% of the monthly average river flows remained below the long-term normal range. Lake and turlough levels also increased at 73% of monitored sites, with 64% below the long-term normal range. Groundwater levels increased at 68% monitoring locations with 66% remaining below the long-term normal range. Of the five spring flows monitored, 4 were ‘below normal’ and1 was in the ‘particularly low’ range.
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