Research and analysis

South-east England water situation report: November 2025 summary

Updated 11 December 2025

Applies to England

• Publication for Northern Ireland
• Publication for Scotland
• Publication for Wales

1. Summary

There was 96% of the long term average (LTA) rainfall for November recorded across the South east of England. Storm Claudia passed over Thames (THM) and Hertfordshire and North London (HNL) on 14 November and brought a lot of heavy rain resulting in above average rainfall being recorded in both Areas. In the southern areas, both Kent and South London (KSL) and Solent and South Downs (SSD) recorded below average rainfall for November. The soil moisture deficits (SMDs) fell during the month as would be expected at this time of year, but remained above average for the end of November. Whilst the rainfall reduced the SMDs, most areal units across the south east still had above average SMDs, which has restricted the amount of effective rainfall that could occur.

The river flows generally rose during the month across all indicator sites with some sites responding to storm Claudia very robustly, other sites the response was much more muted. Flows ranged from below normal to above normal, but most key indicator sites were normal for November. There were 21 fluvial flood alerts issued during November across the south east. The groundwater levels continued to decline during November at around half of the indicator sites, despite the average rainfall. Levels have increased or just turned from the lowest point as would be expected at this time of year at the remaining sites.

2. Rainfall

There was 96% of the LTA rainfall for November recorded across the South east of England. Storm Claudia passed over THM and HNL on 14 November and brought a lot of heavy rain resulting in 122% and 104% LTA being recorded in each area respectively. Meanwhile, in the southern areas, both KSL and SSD recorded below average rainfall for November. The top 5 highest daily totals for the south east were all recorded across THM on 14 November. The highest daily total for the south east was 57.2mm, recorded at Little Rissington, THM on 14 November. The wettest days were 10, 14 and 22 November when over a third of the monthly total rainfall, on average, was recorded. The 10 November was the wettest day in KSL when all top 5 daily totals were recorded. All top 5 daily totals were recorded across SSD on 22 November. The 14 November was the wettest day across THM and HNL. Despite all the rainfall throughout the month, there were also 10 ‘dry’ days (less than 0.2mm rainfall).

3. Soil moisture deficit and recharge

The SMDs fell during the month as would be expected at this time of year, but remained above average for the end of November. The heavy rainfall over THM in particular reduced the SMDs by around two thirds but remained above average for November. SMDs in HNL and KSL also fell sharply during the month, but also remained above average. The only exception was in SSD where SMDs also fell sharply and were reduced to zero in most of the areal units in the area and ended the month well below average for the end of November. 

Whilst the rainfall reduced SMDs, most areal units across the south east still had SMDs above average, which restricted the amount of effective rainfall that could occur. Both THM and HNL had well above average SMDs in a number of areal units and there was only around a quarter of the LTA effective rainfall. In SSD where SMDs were substantially reduced during last month and this, there was around three quarters of the LTA for effective rainfall.

4. River flows

The river flows generally rose during the month across all indicator sites with some sites responding to storm Claudia very robustly, other sites the response was much more muted. Flows ranged from below normal to above normal, but most key indicator sites were normal for November. Flows at Marlborough on the river Kennet (THM) were below normal and the lowest since 2022 for the month. The two sites that were above normal were both Chalk streams in HNL that have remained high, being well supported by healthy groundwater levels. One of these sites, Panshanger on the river Mimram, was the highest November flow since 2024. There were 21 fluvial flood alerts issued during November across the south east.

5. Groundwater levels   

The groundwater levels continued to decline during November at around half of the indicator sites, despite the average rainfall. However, the persistent SMDs prevented much effective rainfall to occur and therefore limited recharge to the aquifers. Levels have increased or just turned from the lowest point as would be expected at this time of year at the remaining sites. Levels ranged from exceptionally low (Chipstead, KSL) to normal, where most sites ended the month at normal levels for November.

6. Reservoir stocks

The reservoir stocks have all generally risen across the south east. However, stocks remained below average for November at all reservoirs except Farmoor (THM) that ended the month close to the LTA and Lower Lee (HNL) and Weir Wood (KSL) that were both higher than average for November.

Author: groundwaterhydrology@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.