September: A changeable, unsettled and sometimes very warm month

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. 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. 

The assessment is contained in the latest monthly hydrological summary for the UK, the most authoritative analysis of water resources status in the country. The monthly summaries are produced by the National Hydrological Monitoring Programme, operated by the Centre for Ecology & Hydrology in conjunction with the British Geological Survey.

UK River Flows - April to September 2016

In some areas, a significant proportion of the monthly rainfall total was associated with intense convective downpours mid-month, when surface water flooding, along with lightning damage, caused severe disruption and localised property flooding. 

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. 

Average river 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. 

Summary author Jamie Hannaford said, "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.”

A PDF of the full 12-page September 2016 summary can be downloaded here.

The monthly summary is a look back at hydrological events occurring in September 2016. Latest information on flood warnings is provided by the Environment Agency, Natural Resources Wales and Scottish Environment Protection Agency (flood warnings for Northern Ireland are not available).

The Centre for Ecology & Hydrology jointly operates the National Hydrological Monitoring Programme (for the UK) in conjunction with the British Geological Survey. NHMP scientists produce the UK Monthly Hydrological Summary which assesses rainfall, river flows, groundwater and reservoir levels. They also operate the UK’s National River Flow archive.

The NHMP also has a remit to analyse major flood and drought events in the UK and analyse long-term trends in UK hydrological data. The UK Monthly Hydrological Summary is normally published on, or before, the tenth working day, of the following month. A Hydrological Outlook for the UK is also available, and is updated monthly. The latest Outlook can be viewed here.

Additional information

Read the full September 2016 Hydrological Summary for the UK

Details of the National Hydrological Monitoring Programme

Latest Hydrological Outlook for the UK

National River Flow Archive

 

 

 

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