Research and analysis

South-east England water situation report: October 2025 summary

Updated 12 November 2025

Applies to England

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

1. Summary

During October, 2 named storms crossed the South east of England. The first was Storm Amy, which crossed the south east between 3 and 4 of the month and the second was Storm Benjamin which impacted the south coast on 22 October. These storms accounted for 15% and 23% of the monthly total rainfall respectively. In total, the South east of England received 108% of the long term average (LTA) rainfall for October.

The soil moisture deficits (SMD) started the month at significantly greater than the LTA, dropped slightly after Storm Amy, then rose up to a peak on 18 October. However, by the end of the month, the SMDs for Solent and South Downs (SSD) ended the month below the LTA and for Kent and South London (KSL) were close to the end of month LTA. These were significantly lower than the SMDs for both Thames (THM) and Hertfordshire and North London (HNL). There was about a third of the LTA recharge during the month.

The recession during the summer continued for all the flow indicator sites. Despite the rainfall, fifteen of the 21 indicator flow sites were in the normal range for October as their catchments had such high SMDs. The steady decline of groundwater levels continued during the month for most of the indicator sites. Half of the groundwater indicator sites were in the normal category at the end of the month.

2. Rainfall

During October, 2 named storms crossed the South east of England. The first was Storm Amy, which crossed the south east between 3 and 4 of the month and the second was Storm Benjamin which impacted the south coast on 22 October. These storms accounted for 15% and 23% of the monthly total rainfall respectively. In total, the South east of England received 108% of the LTA rainfall for October. However, SSD and KSL were much wetter than the north, with 116% and 123% of the monthly LTA respectively, largely as a result of Storm Benjamin on 22 October. By contrast, THM received 92% and HNL 89% of the LTA for October.

The highest daily rainfall total of 52.7mm was recorded at Brockenhurst (SSD) on 19 October. However, the top 5 daily rainfall totals in KSL were all recorded on 22 October and were greater than 40mm.

On average there were 16 ‘dry’ days (less than 0.2mm rainfall in a day) during the month and the rainfall totals from 19 October to the end of the month accounted for 79% of the monthly total on average.

The 7 months ending in October were the driest since 2003 for both THM and HNL and a number of their areal units, including Cotswolds East, Loddon and Enborne (all THM), and Lee Chalk and Chilterns East (both HNL). Most areal units had their driest 12-month period ending in October since 2022.

3. Soil moisture deficit and recharge

The SMDs started the month at significantly greater than the LTA, dropped slightly after Storm Amy, then rose up to a peak on 18 October. They fell in response to the rainfall which followed on the next 5 days, then again in response to the rainfall on 31 October. However, by the end of the month, the SMDs for SSD ended the month below the LTA and for KSL were close to the end of month LTA. Both HNL and THM SMDs remained significantly higher than the LTA. There was about a third of the LTA recharge during the month.

4. River flows

The recession during the summer continued for all the flow indicator sites. There was some muted response to the rainfall with the groundwater fed rivers. However, Lymington River at Brockenhurst (SSD) and the Rother at Udiam (KSL) responded quickly to the rainfall at the end of the month as the SMDs had been significantly reduced by the storms. Both these rivers drain impermeable catchments. Despite the rainfall, fifteen of the 21 flow indicator sites were in the normal range for October as their catchments had such high SMDs. The Mimram at Panshanger and the Ver at Colney Street (both HNL) were in the above normal category, still showing the impact of relatively high groundwater levels in the Lee Chalk during the last year. Two fluvial flood alerts were issued during the month.

5. Groundwater levels   

The steady decline of groundwater levels continued during the month for most of the indicator sites. The exceptions were Jackaments (Oolites, THM), Carisbrooke (Chalk, SSD) and Riddles Lane (Chalk, KSL). Since there has only been on a third of the LTA recharge owing to the high SMDs during October, it is unlikely that the groundwater levels will respond quickly at the slower responding boreholes. Half of the groundwater indicator sites were in the normal category at the end of the month. Rockley (Chalk, THM) levels were exceptionally low for October and both Chilgrove (Chalk, SSD) and Chipstead (Chalk, KSL) were notably low.

Four of the groundwater indicator sites were at their lowest levels since 2022, including Chilgrove (SSD) which had the second lowest October level on record.

6. Reservoir stocks

Some reservoir stocks have started to increase in response to the rainfall during the month. However, Bough Beech, Bewl and Powdermill (all in KSL) continued to decline during October. All of the reservoirs remained below the LTA for September with the exceptions of Weir Wood (KSL) and the Lee Valley (HNL) which ended the month above the LTA.

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.