This month has been the wettest May since 1983 but it is unlikely to have any impact on the drought in the South East of England, say forecasters.
Reservoirs have been partly replenished
The week of 17-23 May was the wettest of the year so far in England and Wales, said the BBC Weather Centre.
But, a day before the UK's first drought order for 11 years, there is no suggestion the water shortage will end.
BBC meteorologist Jay Wynne said: "It's been wet in May but it's not going to have an impact on the current drought."
He said this May was already the wettest in England and Wales for 23 years, with nearly a week left.
"It has been a very wet May but sadly, none of that water goes down your hosepipe," he said.
"It is a bit of a conundrum to some people, but unless the rain falls right on top of the reservoir it will not get there immediately.
"A lot of that water is absorbed by the land and used by the vegetation and a lot simply evaporates, so it takes an awful long time for that water to filter back down to the reservoirs and even longer to fill up the aquifers.
"The real problem is that the aquifers are dry."
It would take a really prolonged spell of above average rainfall to make up for the 18 months of dry weather, he said.
Rain stopped Test cricket at Edgbaston
The Met Office's summer forecast also raises doubts that enough rain will fall this summer to re-fill the aquifers.
On its website, it says: "Prospects for rainfall across the UK through the summer months are also uncertain, but it is unlikely that rainfall will be sufficient to alleviate the water shortages affecting some regions."
The drought order which starts on Saturday is in the Sutton and East Surrey Water region and covers businesses as well as homes.
The ban will include watering sports grounds and washing cars, trains and aircraft with a hosepipe.
It will be little comfort to people living there that sunshine and showers are predicted throughout the UK over the Bank Holiday weekend, with Sunday the best day overall.
But Mid Kent Water and Southern Water said recent rain meant they could hold off on implementing drought orders.