Thames water situation: November 2025 summary
Updated 11 December 2025
Applies to England
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1. Summary
Thames area received 102mm of rainfall in November, which was 122% of the long term average (LTA). Soil moisture deficits (SMD) decreased across Thames area from 123mm in October to 45mm by the end of November. The majority of monthly mean river flows were normal for the time of year. Groundwater levels decreased at 3 of the indicator sites, and increased at 8. The majority are normal for the time of year. Farmoor reservoir is above average for the time of year, while the Lower Thames reservoirs are below average.
2. Rainfall
Thames area received 102mm of rainfall in November, 122% of the LTA. Cherwell, and Cotswolds East areal units, in the north of Thames area, received exceptionally high rainfall, while the remainder of the areal units in the northern half of the area received notably high or above normal rainfall. All units in the southern half of Thames area were normal for the time of year. The wettest day was 14 November. Two rain gauges in Cotswolds West; Little Rissington and Bourton, received 57.2mm and 56mm respectively.
3. Soil moisture deficit and recharge
SMD decreased across Thames area, from 123mm in October to 45mm by the end of November. However, this is still above the average of 34mm usually expected at this time of year. Three areal units, Cotswolds East, Berkshire Downs, and Cherwell, are now below their respective low term averages, while, Cotswolds West SMD is at 0mm.
4. River flows
Monthly mean river flows increased at all indicator sites in November. All sites, apart from the groundwater fed Kennet at Marlborough, which is below normal, are normal for the time of year. By month end, daily mean flows at the rivers Ock at Abingdon, and the Cherwell at Banbury were above normal.
5. Groundwater levels
Groundwater levels declined at 3 indicator sites. Two in the Chalk (Gibbet Cottages and Stonor Estate), and one in the Lower Greensand (Frith Cottage). However, Frith Cottage remains notably high. Levels at 8 indicator sites increased in November, and the majority are normal for the time of year. Ampney Crucis (Great Oolite) is now notably high, Rockley (Chalk) is now notably low, while the Flashes (Lower Greensand) is now exceptionally high.
6. Reservoir stocks
Reservoir stocks in Farmoor increased from 87.1% to 92.6%, while the Lower Thames reservoirs also increased from 61.5% to 70.6%. Farmoor is now above the LTA for November, however the Lower Thames is still below.
7. Environmental impact
During November 19 flood alerts were issued on rivers in the Thames area. At the end of November, 3 abstraction licences were being constrained in the area to protect water resources and the environment.
Author: Thames Area Groundwater Resources and Hydrology, enquiriesWT@environment-agency.gov.uk
Contact Details: 030708 506 506
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.