September was changeable and unsettled at times, but many areas saw a good deal of summery weather with some very warm spells, particularly in the south east. Heatwave conditions in southern England during the second week brought the highest daily maximum temperature of 2016, with 34.4°C recorded at Gravesend on the 13th – the highest September maximum temperature since 1911. For the month as a whole, it was the equal second warmest September since 1910. September rainfall was near-average at the national scale, but there was a marked west/east contrast, with much of eastern England receiving below average rainfall. In some areas, a significant proportion of the monthly total was associated with intense convective downpours mid-month, when surface water flooding, along with lightning damage, caused severe disruption and localised property flooding. However, river flow responses were muted and average flows for September were predominantly in the normal range. Given the dry, warm conditions soil moisture deficits (SMDs) persisted in the south east and remained above average. Correspondingly, groundwater levels continued their seasonal recession, with levels remaining mainly in the normal range or above. While a few south-western reservoirs saw stocks more than 15% below average, stocks were otherwise above average, and substantially so in most major impoundments in northern and western Britain. The water resource outlook therefore remains healthy entering the winter half-year.
The full Hydrological Summary can be found here.