Research and analysis

Solent and South Downs 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

Solent and South Downs (SSD) had above average rainfall in October, receiving 116% (116.9mm) of the long term average (LTA) of 100.5mm. Monthly mean river flows for October ranged from below normal to normal across SSD. End of month groundwater levels for October ranged from exceptionally low to above normal. Soils across SSD ended the month wetter than the LTA for October.

End of month reservoir stocks were below average at Ardingly Reservoir (Ouse) and at Arlington Reservoir (Cuckmere).

2. Rainfall

SSD had above average rainfall in October, receiving 116% (116.9mm) of LTA (100.5mm). The highest rainfall totals in Hampshire were in the Lymington areal unit which received 125% (125.3mm) of LTA (100.1mm). While, in Sussex the highest rainfall totals were in the Pevensey Levels areal unit with 126% (121.7mm) of LTA (96.3mm). The Test Chalk areal unit received the lowest rainfall with 93% (89.1mm) of LTA (95.3mm) during October. 

There were 3 wet periods in October with widespread rainfall in the SSD. At the beginning of the month there were 2 wet days between 2 and 3 October with almost 20% of the month total rain. After this there was settled dry weather for 2 weeks and then more unsettled weather in the second half of the month. Over 55% of the rainfall in this month fell between 19 to 22 October in only 4 days. Then the third wet period between 29 to 31 October brought about 20% of the month total rainfall.

The wettest day was 19 October. On this day the highest daily total of 52.7mm was recorded at Brockenhurst RG (Lymington), and 51.7mm at Otterbourne RG (East Hampshire Chalk). On the second wettest day, 22 October, rainfall totals over 40mm were recorded at Hastings Baldslow TBR, at Pevensey RG and at Cowbeech RG.

The last 9 months has been the eighth driest February to October period on record for the Test Chalk areal unit. For the 24-month period (starting November 2023) it was the eighth highest rainfall total for the East Sussex Chalk areal unit. All these statistics are based on records going back to 1871.

3. Soil moisture deficit and recharge

Soils across SSD ended the month wetter than the LTA for October.

4. River flows

Monthly mean river flows for October ranged from below normal to normal across SSD.

Flows were below normal on the:

• River Test at Broadlands
• River Meon at Mislingford

Flows were normal on the:

• River Test at Chilbolton
• River Itchen at Allbrook and Highbridge
• River Lymington at Brockenhurst
• River Medina at Blackwater
• River Rother at Iping Mill
• River Ouse at Goldbridge
• River Cuckmere at Cowbeech
• River Arun at Alfoldean
• River Wallington at North Fareham
• River Adur at Sakeham

5. Groundwater levels    

End of month groundwater levels for October ranged from exceptionally low to above normal across SSD.

Groundwater levels were exceptionally low at:

• Chilgrove (West Sussex Chalk)

• Beeding Hill (West Sussex Chalk)

Groundwater levels were below normal at:

• Lopcombe Corner (Test Chalk)

• Catherington (East Hampshire Chalk)

• Houndean Bottom (East Sussex Chalk)

Groundwater levels were normal at:

• Clanville Gate (Test Chalk)
• West Meon (East Hampshire Chalk)

• Harting Common (Western Rother Greensand)

• Carisbrooke Castle (Isle of Wight)

• Youngwoods Copse (Isle of Wight)

Groundwater levels were above normal at:

• Preston Candover (East Hampshire Chalk)
• Cornish Farm (East Sussex Chalk)

The groundwater levels at Chilgrove and at Beeding Hill (both West Sussex Chalk) were the second lowest October levels. These statistics are based on records going back to 1836 and 1979, respectively.

6. Reservoir stocks

End of month reservoir stocks were below average for both Ardingly and Arlington Reservoirs. Ardingly Reservoir (Ouse) was at 30.2% of total capacity (LTA 70%) and Arlington Reservoir (Cuckmere) was at 49.2% of total capacity (LTA 61.9%).

7. Environmental impact 

7.1 Abstraction licence restriction

At the start of October there were 14 licence restrictions in force, which decreased to 4 licence restrictions by the middle of the month. By the end of the month 6 licence restrictions were in place. These included:

• one licence on the Ouse
• two licences on the River Meon
• four licences on the Isle of Wight
• one licence on the Walkford Brook
• one licence on the Bremere Rife
• two licences on the River Ems
• four licences on the Western Rother
• one licence on the Loxwood Stream, Arun catchment

7.2 Flood Alerts and Warnings in Force

There were 8 Flood Alerts issued in October, all fluvial. One was issued on the Isle of Wight, 2 in Hampshire and 5 in East Sussex.

There were no Flood Warnings issued in October.

Author: HydrologySSD@Environment-agency.gov.uk

Contact Details: 03708 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.