July featured a mixture of sunshine and showers bookending a warm and briefly very hot spell mid-month. Aside from this spell, periods of persistent unsettled weather delivered substantial rainfall predominantly to northern and western regions of the UK, resulting in an exaggerated north-west / south-east rainfall gradient.
Whilst parts of Scotland, Northern Ireland, northern England and north Wales were considerably wetter than average, much of southern England registered less than half of the average rainfall. For England it was the driest July since 1999.
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.
The summary shows that changes in soil moisture deficits (SMDs) in July reflected the rainfall gradient, with soils wetting up in the north and west and SMDs increasing in the south and east. River flows for July were above average across the majority of the UK, substantially so in western Scotland, Wales and East Anglia, but below normal in parts of south‑west England. Groundwater levels fell or remained stable in almost all index boreholes (as expected for the time of year) but largely remained in the normal range or above. Reservoir stocks for England & Wales fell slightly but remained above average for the time of year, appreciably so for some impoundments in the north and west.
Summary author Simon Parry from the Centre for Ecology & Hydrology said, "With groundwater levels and reservoir stocks generally near or above average, the water resources outlook remains healthy for the remainder of the summer and early autumn."
The monthly summary is a look back at hydrological events occurring in July 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.