Thames water situation: June 2026 summary
Updated 14 July 2026
Applies to England
© Crown copyright 2026
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June was a month of 2 halves. June saw 69mm of rainfall, which was 131% of the long term average (LTA), however one-third of the month’s rain fell on 1 June, and there was little to no rain from 12 June. It was also the hottest June on record. Despite the rainfall, soil moisture deficits (SMDs) were much drier than the LTA. Monthly mean river flows decreased at the majority of sites in Thames area in June. Two-thirds of our indicator sites were normal for the time of the year. However daily mean flows decreased towards the end of the month. 7 sites were below normal, 2 sites were notably low, while 2, Kingston and Windsor, both on the Thames, were exceptionally low for the time of year. Groundwater levels continued their seasonal decline, with the majority ending the month normal for the time of the year.
1. Rainfall
Thames area received 69mm of rainfall in June, 131% of the LTA. One-third of the month’s rain fell on 1 June, 22mm, and the first 11 days accounted for 89% of the month’s rain. The remainder of the month had little to no rain, apart from 5mm on 22 June. This coincided with the warmest June on record. The majority of rainfall units received above normal rainfall for the time of year, while central Thames area and Cherwell in the north received normal rainfall. Over the past 3 months Thames area has received below normal and notably low rainfall.
2. Soil moisture deficit and recharge
Despite the rainfall, the heatwave at the end of June increased SMDs to 117mm, well above the 67mm LTA. The Enborne and Loddon had a SMDs of 135mm and 132mm respectively. Due to the prevailing dry conditions, there was no significant effective rainfall across most of our areal units.
3. River flows
Monthly mean river flows decreased at the majority of sites (13 out of 15) in Thames area in June. Two-thirds of our indicator sites were normal for the time of the year. Two sites were above normal, 2 were below normal and one, the River Coln at Bibury was notably low. The rain at the start of the month supported monthly mean totals, but the heatwave has caused daily mean flows to decrease towards the end of month. Seven sites were below normal, 2 sites were notably low, while 2, Kingston and Windsor, both on the Thames, were exceptionally low for the time of year.
4. Groundwater levels
Like last month, groundwater levels continued their seasonal decline at all our indicator sites in June, and mostly remained normal for the time of the year (7 out of 11 sites). Levels at Jackaments Bottom (Inferior Oolite) remained notably low. The Lower Greensand sites continued to have higher levels than typical for the time of year with above normal levels at Frith Cottage and notably high levels at The Flashes. The only change was Rockley (Berkshire Downs Chalk) where groundwater levels fell more rapidly than typical for the time of year and became below normal.
5. Reservoir stocks
Farmoor Reservoir slightly increased and ended the month at 98.9%, above the LTA for the time of the year whereas the Lower Thames Reservoirs decreased and ended the month at 88.1%, below the LTA.
6. Environmental impact
At the end of June, 32 abstraction licences were having their flow constrained in order to protect 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.