Folklore says today's rain heralds 40 days of downpours - and forecasters have not dismissed the possibility.
Legend has it that showers on July 15 - St Swithin's Day - are an omen for a lengthy spell of wet weather.
But though today's deluges will not blight the entire summer, experts did not rule out the potential for some rain every day.
Forecasters said many parts of the UK would be deluged with showers this morning following heavy rain in the past 12 hours.
Met Office forecaster Charles Powell said 25mm to 30mm fell overnight and warned bad weather and unseasonably strong winds will continue into tomorrow.
Gusts of up to 60mph are predicted in the South West, hitting coastal areas with some force.
This could result in tiles being whipped from roofs, with the additional risk of trees being uprooted in exposed areas, he said.
"We are getting close to storm force winds which could do some damage," he added.
"It will be quite a showery and blustery day across the UK with fairly heavy rain pushing south."
But he said that though the unsettled weather is set to continue "for the foreseeable future", it will be broken up by sporadic sunny spells.
While it is good news for gardeners, those hoping to catch some rays over the weekend are likely to be disappointed - wet spells are forecast for Saturday and Sunday.
Asked whether the ancient legend might this year prove accurate, forecasters expressed some doubts.
Matt Dobson, of MeteoGroup, the weather division of the Press Association, said: "There's usually at least one dry day in a summer - it's unlikely but it is possible."
Saint Swithin was a ninth century Saxon bishop.
Legend has it that the removal of the saint's bones from his preferred burial place outside Winchester Cathedral to another location coincided with 40 days of continuous rain and storms.
Since then, rainfall on July 15 has been taken as an omen of impending miserable weather.
Today also marks another important day in the meteorological calendar as one of the UK's greatest meteorologists, George James Symons, is honoured.
Aged just 22 he founded the British Rainfall Organisation in 1860 and over the next 40 years published detailed annual summaries of rainfall over the British Isles.
Now, 110 years after his death in 1900, this system still forms the backbone of rainfall observing systems and records in the UK.
The meteorologist was buried at London's Kensal Green Cemetery in a grave that fell into disrepair.
Members of the Royal Meteorological Society renovated the site and will gather there today for a rededication event.