Storm Austen won't end the drought: England's reservoirs are 54% full and need months of rain

What Friday brings

The Met Office named Storm Austen on Tuesday, the first named storm of the season. Its warnings, read on Thursday morning, are for wind. An amber warning covers Cornwall, Devon, the Isles of Scilly and Plymouth from 3am to 10am on Friday. Yellow wind warnings run from midnight to 2pm on Friday across south-west England, Hampshire, the Isle of Wight, Sussex and Kent, south and mid Wales, and Herefordshire. The Met Office says gusts of over 70mph are possible on the most exposed coasts, with 50-60mph more widely in the yellow area. Our wind warning story has the detail and what to do.

On rain, the Met Office says: "Rain is an additional hazard, with 20-30mm in many places and higher totals possible over higher ground in the west and further north on Friday." It adds that further periods of wind and rain are likely through the weekend and into the start of next week, with the heaviest rain more likely in western areas. The only rain warnings in force are in Scotland, from 6am on Friday to 3am on Saturday. There is no rain warning for England.

Where England's water stands

The Environment Agency's weekly report for 9 to 15 October, the newest published on 22 October, opens: "The drought situation in England has continued to worsen, despite some rainfall across parts of the country."

National reservoir storage in England was 54% of capacity in the week ending 13 October, around 21% below the long-term average for the time of year. Eighteen reservoir groups were under half full, and 11 reservoirs or groups were classed as exceptionally low, including Ardingly, Wimbleball, Colliford, Chew Valley, Hanningfield, Grafham Water and Rutland Water.

In the Environment Agency's weekly figures, which our drought tracker records, England's reservoirs were 82.9% full in the week ending 7 July. They have fallen almost every week since.

A wetter week, and storage stayed at 54%

The clearest sign of how little one wet spell does is in the same report. The Environment Agency says: "It has been a wetter week across much of England, particularly in the north-west." Rainfall that week ranged from 10mm in central and south-east England to 33mm in the north-west.

Yet over two-thirds of reservoirs still recorded a fall in storage in the week ending 13 October. Ten, mainly in northern England and Wales, rose. "Overall, England storage remains at 54%," the agency says.

The Environment Agency notes that October as a whole remains much drier than normal: England as a whole had received 26% of its long-term average October rainfall by 15 October, from 18% in south-east and south-west England to 41% in the north-west. The agency's verdict: "Further significant rainfall is needed to return to normal water resource conditions for many water companies."

What it would take: 120% of normal rain for seven months

On 16 September a press release from the Environment Agency, Defra and water minister Emma Hardy, issued after a National Drought Group meeting, said: "New research has shown we need 120% of typical rainfall over the next seven months for all areas to be considered out of drought."

That is a season's worth of wetter-than-normal weather, not a storm. Even a very wet Friday is one day out of roughly 210. Our guide to the hosepipe bans this winter goes through what each water company has said about lifting its ban.

Rain shows up in rivers first

Rain does real good, just not to reservoirs first. As the Environment Agency's chief executive said on 16 September: "A few weeks of rain cannot reverse the deficit we face from the very dry spring and summer."

In the wetter week to 15 October, river flows rose at most of the Environment Agency's reporting sites, though most were still below normal for the time of year. Groundwater levels were still in their usual seasonal decline at most sites.

Soils are still well short too. In the UK Centre for Ecology & Hydrology's COSMOS-UK network, 26 of the 28 English sites we could classify were drier than normal for the time of year in the seven days to 20 October (the newest data is provisional). Sites in Northern Ireland, Scotland and Wales were mostly normal. On farmland, the European Drought Observatory's indicator had 45 of the 47 English points we read in drought warning or alert for 21 to 30 September. You can follow the rain as it falls on our rainfall tracker.

Bans and drought status today

Ten water companies have temporary use bans (hosepipe bans) in force, and the Environment Agency reported no changes in the latest week: Affinity Water (Central and East regions), Anglian Water (excluding Hartlepool), Bristol Water, Cambridge Water, Essex & Suffolk Water, Southern Water (Hampshire and the Isle of Wight), South East Water, South West Water (excluding Bournemouth), Thames Water and Wessex Water. Our hosepipe ban tracker lists each one.

Since the government's declaration on 15 October, parts of four Environment Agency areas have been in severe drought: Wessex; Devon, Cornwall and the Isles of Scilly; Solent and South Downs; and Kent and South London. The agency lists ten areas in drought: East Anglia, Hertfordshire and North London, Thames, Devon, Cornwall and the Isles of Scilly, the West Midlands, Kent and South London, Solent and South Downs, the East Midlands, Lincolnshire and Northamptonshire, and Yorkshire, which moved into drought on 9 October.

Not everywhere is in drought. The Northeast, Cumbria and Lancashire, and Greater Manchester, Merseyside and Cheshire are in prolonged dry weather, the stage before drought.

The outlook is the Met Office's, not ours

The Met Office's three-month outlook for October to December, issued on 28 September, says: "There is double the normal chance of this period being wet overall." A wetter-than-normal season is what the 120% figure needs, but an outlook gives chances, not a promise. The next outlook is due on 26 October, and the Environment Agency's next weekly report covers 16 to 22 October, before Storm Austen's rain.