Research and analysis

Water situation: December 2024 summary

Updated 13 January 2025

Applies to England

Overall rainfall for England in December was below average. It was a drier month across southern areas with nearly two-thirds of hydrological areas receiving below average rainfall during December but above average rainfall fell across northern areas. Soil moisture deficits (SMD) were close to zero across most of England with soils in many areas wetter than expected for the time of year. Monthly mean river flows increased at most sites during December and flows at the majority of sites continued to be classed as normal for the time of year. Groundwater levels increased during December at more than four-fifths of reporting sites and all sites are classed as normal or higher. Reservoir stocks increased across England during December, ending the month 89% full.

Rainfall

The rainfall total for England for December was 82.2mm which represents 98% of the 1961 to 1990 long term average (LTA) for the time of year (89% of the 1991 to 2020 LTA). Nearly two-thirds of hydrological areas received below average rainfall during December. The wettest hydrological area relative to LTA was the Cheshire Rivers Group in north-west England which received 164% of the LTA rainfall. In contrast, the Otter, Sid, Axe and Lim hydrological area in south-west England was the driest hydrological area having received 45% of LTA rainfall in December.

Rainfall totals during December were classed as normal at 56 hydrological areas (40%) we report on. Fifty-one areas (37%) across south-west and south-east England were classed as below normal for the time of year, with 3 sites (2%) in the south-west classed as notably low. Rainfall totals across 26 hydrological areas (19%) chiefly across central and northern England were classed as above normal, with 3 areas (2%) in the north-east of the country recording notably high rainfall for the time of year. At a regional scale, rainfall was classed as above normal in north-east and north-west England and below normal in south-west England. Rainfall for east, south-east and central England as well as England as a whole was classed as normal.

The 3-month cumulative rainfall totals show rainfall was classed as normal across the majority of hydrological areas. The 6-month cumulative rainfall totals were classed as normal or higher for nearly all hydrological areas with notably and exceptionally high rainfall being recorded for central and south-eastern England. The 12-month cumulative totals show that half of hydrological areas are classed as having received exceptionally high rainfall.

Soil moisture deficit

As expected for this time of year, SMDs are close to zero across most of England as soils remain at field capacity from wet conditions during the preceding months. Some slight deficits persist across parts of eastern England.

At the end of December, soils continue to be wetter than expected in many regions across England, with only the north-west and south-west reporting SMDs of around average for the time of year.

River flows

Monthly mean river flows increased at the majority of indicator sites during December. Flows at all but 2 sites are classed as normal or above for the time of year.

Nearly half of sites (47%) had monthly mean river flows classed as normal. Seventeen sites (31%) had flows classed as above normal and 7 sites (13%) predominantly in southern England reported monthly mean flows classed as notably high. Three sites (5%) had monthly mean flows classed as exceptionally high with the River Ver at Hansteads recording its highest ever December monthly mean river flow since records began in 1956. Two sites (4%), both in south-west England, had flows classed as below normal for the time of year.

All regional index sites saw an increase in monthly mean river flows in December compared to November. Naturalised flows at Kingston on the River Thames were classed as exceptionally high for December and the Bedford Ouse at Offord and the River Dove at Marston-on-Dove reported above normal monthly mean flows. The Great Stour in south east England, the River South Tyne in north-east England, the River Exe in south-west England and the River Lune in the north-west all had monthly mean flows classed as normal for the time of year.

Groundwater levels   

At the end of December, more than four-fifths of indicator sites reported an increase in groundwater levels. All groundwater indicators sites were classed as normal or above for the time of year, with the majority (58%) classed as either normal or above normal.

Three sites recorded their highest end of December groundwater level on record (record start given in brackets), including:

• Weir Farm (1983) in Bridgnorth Sandstone in central England
• Coxmoor (1990) in Idle Torne Sandstone in central England
• Priors Heyes (1972) in Permo-triassic sandstone in central England

Groundwater levels increased at all but one of the aquifer index sites and all were classed as normal or above for the time of year. Exceptionally high groundwater levels for the time of year were recorded at Weir Farm in the Bridgnorth Sandstone (central England) and Stonor Park in the south-west Chilterns Chalk (south-east England). Groundwater levels at Redlands Hall in the Cam and Ely Ouse Chalk in east England and Skirwith in the Carlisle Basin Sandstone in north-west England were classed as notably high and above normal respectively. Little Bucket in the East Kent Stour Chalk, Jackaments Bottom in the Burford Jurassic Limestone, Chilgrove in the Chichester Chalk all in south-east England and Dalton Estate Well (Hull and East Riding Chalk) in north-east England were classed as normal for the time of year.

Reservoir storage

During December reservoir storage increased at all but 3 of the reservoirs and reservoir groups that we report on. The largest stock increases were at the Derwent Valley in central England and Wimbleball in south-west England where storage increased by 18% and 15% respectively.

More than half (58%) of the reservoirs we report on were classed as normal for the time of year. Two (6%) reservoirs Casington and Ogston in central England and the Teesdale group in north-east England were classed as exceptionally high for time of year. Haweswater and Thirlmere and the Dee system, both supplying north-west England, were classed as notably low for the time of year as they were impacted by planned maintenance in the resource zone and drawdown for reservoir safety work respectively.

At a regional scale, total reservoir storage increased across the country, with south-east and south-west England both reporting increases of 8%. For England as whole, total storage increased during December by 6% ending the month at 89% .

Forward look

January began with cold conditions across the country and snow for many areas, bringing precipitation totals already more than a third of the LTA for the month. Towards the middle of January high pressure is likely to linger in the south, bringing settled conditions for most of the country. Fog may develop in areas where winds are lighter, particularly the south. Southern and eastern areas will see colder temperatures, while the north and west are likely to be around or above average for the time of year. At the end of January more unsettled conditions are expected to move in from the north, bringing milder conditions with wind and rain becoming more likely.

For the 3 month period between January and March there is a higher than average chance of it being milder, wetter and windier than would be expected. Cold spells are more likely early in the period. Wet and windy conditions have increased likelihood in February and March, and stormy spells are likely.

Projections for river flows at key sites

By the end of March 2025, river flows across the country have the greatest chance of being normal or higher. Flows in south-east England having a greater than average chance of being above normal or higher, except those in Kent and Sussex where below normal flows have the greatest chance of occurring.

By the end of September 2025, river flows across the country have the greatest chance of being normal or higher. Flows in east and south-east England are mixed with some having a greater than average chance of being above normal or higher, while others have a greater chance of being below normal or lower.

Projections for groundwater levels in key aquifers

By the end of March 2025, groundwater levels across most of England have a greater than average chance of being above normal or higher, particularly in chalk aquifers where groundwater levels remain high. The exception is south west England where normal levels have the greatest chance of occurring.

By the end of September 2025, groundwater levels across England have the greatest chance of being normal or higher.

Author: National Water Resources Hydrology Team, nationalhydrology@environment-agency.gov.uk

All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained in this report.