Research and analysis

Wessex water situation: August 2026 summary

Updated 14 September 2026

Applies to England

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

1. Summary

August 2026 began dry with some 70% of total rain recorded between 26 and 30 August. An average of 46mm of rain fell across Wessex in August, 64% the long term average (LTA). Despite the rain, the latest 2 month period is the fourth driest July to August on record for Wessex. Over the last 6 months, Wessex reported 58% LTA rainfall which is the sixth driest March to August on record. This follows on from the third wettest 6-month period on record from September (2025) to February (2026) for Wessex. Soil moisture deficit (SMD) rose through the early part of August in response to the dry weather and reached a historic maximum in late August. SMD fell after 26 August but still ended the month well above the LTA. Daily mean river flows remained low for most of August with some response to rainfall in mid to late August. Monthly mean flows were predominately below normal to notably low. Six sites recorded exceptionally low monthly mean flow, 3 of which were in Wessex Chalk Aquifer catchments. Groundwater levels fell through August with little immediate impact from rain. At the end of the month, Chipley in the west, Wrington in the north and Tilshead in the south all reported exceptionally low groundwater levels. All sites on the Wessex Chalk Aquifer reported below normal to exceptionally low groundwater levels. At the end of August, reservoir storage for Wessex Water and Bristol Water were 41% and 54% capacity respectively.

2. Rainfall

An average of 46mm of rain fell across Wessex in August, 64% the LTA. Despite some light rain, the month started off relatively dry. Approximately 94% of Wessex’s total rain was recorded after 18 August with 70% of August’s total rain recorded between 26 to 30 August. Rainfall was higher in the north than the south of Wessex with majority of hydrological areas receiving below normal rainfall with some receiving normal rainfall. The Axe hydrological area received the most rain in Wessex through August with 76mm (89% LTA)

July and August combined were the fourth driest on record in the Wessex area for this 2-month period. Over the last 3 months, rainfall was recorded as below normal to notably low for almost all hydrological areas across Wessex (66% LTA). Over the last 6 months, Wessex reported 58% LTA rainfall which is the sixth driest March to August on record. In this period the majority of hydrological areas have received exceptionally low rainfall. This follows on from the third wettest 6 month period on record from September (2025) to February (2026) for Wessex. This is reflected by the previous 12 month rainfall reporting as 111% of the LTA.     

3. Soil moisture

SMD increased through the early part of August in response to the dry weather. Despite rainfall in the middle of the month SMD reached a historic maximum in late August. SMD decreased in response to rainfall in late August but by the end of the month SMD was still greater than the LTA. Most hydrological areas recorded a SMD of 101mm to 130mm with some southern hydrological areas recording a SMD of 131mm to 160mm at the end of August. The majority of areas reported SMD 26mm to 50mm greater than the LTA at the end of the month. Some north Wessex areas reported SMD 6mm to 25mm greater than the LTA.

4. River flows

Daily mean river flows remained low across Wessex for most of August peaking towards the end of the month following rain. By the end of August, daily mean river flows tended to be lower at sites supported by the Wessex Basin Chalk aquifer rather than in the north.

Most monitoring sites in Wessex reported below normal to notably low monthly mean river flows in August with 6 sites reporting exceptionally low and one reporting normal. Three sites on the Hampshire Avon were exceptionally low and all other sites supported by the Chalk aquifer were notably low and below normal. Despite this, monthly mean flows in the south of Wessex tended to be a higher percentage of the LTA than the north. The other 3 exceptionally low sites were away from the Chalk aquifer including the River Tone and Bristol Frome.

5. Groundwater levels   

Groundwater levels continued to fall across Wessex in July despite the rainfall in the second half of the month. All monitoring sites recorded below normal to exceptionally low groundwater levels by the end of August except Didmarton which reported as normal. Most monitoring sites on the Wessex Basin Chalk reported notably low groundwater levels with Tilshead falling to exceptionally low. Woodyates continues to fall but remains below normal. 

In north Wessex, Wrington (monitoring Carboniferous Limestone) and Chipley (monitoring Otter Sandstone) reported exceptionally low groundwater levels. Over Compton (monitoring Bridport Sand) was reported as below normal by the end of August.

6. Reservoir storage

Reservoir storage has continued to fall through August for both Bristol Water and Wessex Water. Wessex Water ended the month at approximately 41% capacity which is similar to storage this time last year and in 1995. Bristol Water ended July at approximately 54% capacity which is higher than in 2025 and in 1995.

Author: Wessex Area, hydrology.wessex@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.