Research and analysis

Water situation: May 2025 summary

Updated 13 June 2025

Applies to England

May brought another dry month, with 57% of the long term average (LTA) rainfall being received across England as a whole. Soil moisture deficits (SMD) continued to increase, leaving soils much drier than would be expected across most of England. Monthly mean river flows decreased at most of the sites we report on, with all except one site classed as normal or lower for the time of year. Groundwater levels have continued their seasonal decline, and half were classed as normal at the end of May. Reservoir stocks decreased at all except one site during May, with England as a whole ending the month with 77% storage.

1. Rainfall

During May, England received 32.8mm of rainfall which represents 57% of the 1991 to 2020 LTA for the time of year. Almost all hydrological areas received below average rainfall during May, with just 4 hydrological areas in north-west England receiving above LTA rainfall. Seventy hydrological areas received less than 50% of the May LTA rainfall, including 5 hydrological areas in south-east England which received less than 30% of the LTA. The wettest hydrological area as a percentage of LTA was Kent in north-west England, which received 120% of LTA rainfall (111.7mm). The driest hydrological area as a percentage of LTA was Thanet Chalk which received less than 10mm of rainfall which is 22% of the LTA for the time of year.

Rainfall totals in May were classed as normal or lower for all except one hydrological area. The River Kent catchment in north-west England was the only hydrological area to be classed as above normal for the time of year. Twenty-six hydrological areas (19% of the total) were classed as normal for the time of year. Almost half of hydrological areas were classed as below normal, including most of the north-east of England. Just over a third were classed as notably low, all of which were in central and southern England, and 2 hydrological areas, Cotswolds West and the Lower Severn Estuary were exceptionally low for the time of year.

The 3-month cumulative totals were classed as exceptionally low in the majority of hydrological areas. Fifteen hydrological areas had the driest March to May period since records began in 1871, including:

• 8 in north-east England
• 3 in south-east England
• 4 around the Welsh border in central and south-west England

The south-west was the only region to have hydrological areas in higher bands for the period, with:

• 3 classed as normal
• 5 classed as below normal
• 15 classed as notably low

The 6-month cumulative totals were classed as normal or lower across England, with the majority classified as below normal. The 12-month cumulative totals were classed as normal in more than two thirds of hydrological areas, with most of the remaining areas classed as below normal or lower, and just 2 hydrological areas classed as above normal for the period.

At a regional scale, rainfall was classed as normal in north-west England, notably low in south-east England and below normal in all other regions. It was the fifth consecutive month of below average rainfall in north-west and north-east England, and it remains the driest start to a calendar year since 1929 in the north-east. The north-east has also had the driest 3-month and 4-month periods since records began in 1871. For England as a whole, it was the fourth consecutive month of below average rainfall, and was the driest March to May period since 1893.  

2. Soil moisture deficit

By the end of May, SMD had continued to increase across most of England, except in north-west England and the Welsh border, where soils were wetter following recent rainfall. Soils were driest across south-east, south-west and parts of central and east England.

Soils were drier than would be expected across almost all of England at the end of May, with the only exceptions being a handful of hydrological areas in north-west England were rainfall totals were highest in May. Across south-east England, parts of the south-west and parts of central England, soils were much drier than would be expected for the time of year.

3. River flows

Monthly mean river flows decreased at the majority of our indicator sites in May, with 5 sites seeing an increase in river flows, all of which were in north-west and north-east England, and the River Dee. All except one site were classed as normal or lower for the time of year. The exception was the River Ver in south-east England, which was classed as above normal for the time of year as high groundwater levels continue to support river flows in the catchment. Forty-five sites were classed as normal, below normal or notably low, with 15 sites in each band. Nine sites were classed as exceptionally low, including 3 in north-east England where all sites were below normal or lower for the time of year.

Two sites recorded their lowest May monthly mean flow on record (record start given in brackets), both of which were in north-east England:

• River Till at Heaton Mill (2001)
• River Wear at Witton Park (1972)

For regional index sites, only Haydon Bridge on the South Tyne in north-east England, and the River Lune at Caton in north-west England saw an increase in monthly mean river flows compared to April. The River Lune was normal for the time of year while the South Tyne was classed as notably low as the impacts of dry weather in north-east England continued to be felt. In south-east England, the Great Stour at Horton and naturalised monthly mean flows on the River Thames at Kingston were both classed as below normal for the time of year. The Bedford Ouse at Offord in east England was also classed as below normal. The River Dove at Marston-on-Dove in central England was exceptionally low for the third month in a row. In south-west England, the River Exe at Thorverton was classed as normal for the time of year.

4. Groundwater levels   

At the end of May, all except one of our indicator sites recorded a decrease in groundwater levels as aquifers continued their seasonal recessions. Almost half of all sites were classed as normal for the time of year. One site was classed as exceptionally low. Five sites were classed as below normal, all of which were in chalk aquifers. Three sites were classed above normal, including Crossley Hill and Four Crosses in the sandstone. Two sites were notably high and two were exceptionally high.

Groundwater levels at major aquifer index sites all decreased to the end of May. Jackaments Bottom in the Burford Jurassic Limestone of south-east England, was classed as exceptionally low for the time of year for the second month in a row. Weir Farm in the Bridgnorth Sandstone in central England, was exceptionally high and recorded the highest end of May groundwater level since records began in 1983. In contrast, Skirwith in the Carlisle Basin Sandstone of north-west England, was classed as normal for the time of year. Across chalk aquifers in south-east and east England, groundwater levels were generally normal for the time of year. This included Redlands Hall (Cam and Ely Ouse Chalk), Chilgrove (Chichester Chalk) and Little Bucket (East Kent Stour Chalk). Stonor Park in the South West Chiltern Chalk of south-east England was notably high, as declining groundwater levels brought the site out of the exceptionally high class for the first time since December 2023. In north-east England where conditions have been dry since the start of the year, Dalton Estate Well (Hull and East Riding Chalk) was classed as below normal for the time of year. 

5. Reservoir storage

At the end of May, reservoir stocks decreased at almost all of the reservoirs and reservoir groups we report on. Twelve reservoirs or reservoir groups saw decreases of 10% or more, including the Pennines group in north-west England where storage fell by 15%. Abberton reservoir in east England was the only reservoir to record an increase in stocks by the end of May. A quarter of reservoirs were classed as normal for the time of year, most of which were in east and south-east England. Stithians in south-west England was classed as above normal, and Farmoor in south-east England was notably high for the time of year. Ten reservoirs were classed as below normal for the time of year, and 4 were notably low, including Kielder and Teesdale group in north-east England. The remaining 7 reservoirs, including all the reservoirs and reservoir groups we report on in north-west England, were classed as exceptionally low for the time of year.

Haweswater and Thirlmere remained classed as exceptionally low for the time of year as previously reported planned maintenance and low inflows have impacted the water resource zone. Similarly, the Dee system in Wales which supplies north-west England has been impacted by drawdown for safety works and low inflows, leaving it exceptionally low for the time of year.

The south-east has the highest regional stocks at 92%, while the north-west has the lowest with 62%. All regions are below average for the time of year, with storage in the north-east and north-west, and England as a whole, now lowest on record for the time of year. Storage for England as a whole was 77% at the end of May, as overall stocks dropped by 7% since April.

6. Forward look

June started with unsettled, changeable conditions that brought rain to much of England, particularly the north-west. Conditions are expected to remain unsettled through to the middle of the month, with outbreaks of rain and cloudy conditions for many, although temperatures will be warmer and humidity will be high. Through the second half of June, high pressure is expected to arrive, bringing more settled conditions and drier weather. In late June a return to less settled conditions is expected, with spells of rain, although temperatures are likely to remain above average.

For the 3-month period June to August, there is a higher than normal chance of warmer temperatures, with an increased risk of heatwaves. The chance of a wet or dry period are balanced, although wet weather remains likely. Signals remain weak for the end of the period bringing increased uncertainty.

7. Projections for river flows at key sites

By the end of September 2025, river flows across most of England have the greatest chance of being below normal or lower for the time of year. In south-east England, river flows have a greater chance of being normal or higher for the time of year. By the end of March 2026, river flows across most of England have a greater chance of being normal or lower for the time of year, while in south-east England river flows have a greater chance of being normal or higher for the time of year.

8. Projections for groundwater levels in key aquifers

By September 2025, groundwater levels across most of England have the greatest chance of being normal for the time of year, with the exception of south-west England, where levels in chalk aquifers have a greater chance of being below normal or lower. By March 2026, groundwater levels in east, central, north west and north east England have the greatest chance of being below normal or lower for the time of year. In south west and south east England, the chances are greater that groundwater levels will be normal or higher, particularly in chalk aquifers.

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.