Hydrological Summary for August 2023 Published

With the exception of a few periods of respite, August was largely characterised by a continuation of the unseasonably cool, windy and wet weather that dominated July – although it was nowhere near as exceptional. The August temperature and rainfall for the UK as a whole was near-average but, with low pressure holding sway, a series of Atlantic depressions bought widespread heavy rainfall and surface water flooding, albeit with limited fluvial flood responses. The storms included two named events that were surprisingly late first entries of the 2022-2023 season, highlighting the quiescence of the previous winter. In contrast, much of summer 2023 had a distinctly autumnal feel – following the exceptionally dry and warm June, July and August were unsettled and at times very wet. Correspondingly, soils were unseasonably moist for late summer in many areas, and river flows and groundwater levels were largely in the normal range or above. Reservoir stocks at the end of August were healthy at the national scale (5% above average for England & Wales, and 22% above for Northern Ireland) although a few impoundments continued to track below‑average (below average stocks persist at Colliford and Roadford, while Loch Thom, Ardingly and Celyn & Brenig also saw stocks more than 10% below average). While ongoing vigilance is required in these localities, the early autumn water resource picture is favourable at the national scale. September began with a remarkably arid episode for the time of year, but the current Hydrological Outlook suggests largely normal flows and groundwater levels for autumn. Read the Hydrological Summary.