Weathermen say the South is set for a rainy start to August.
There could be more rain in the next 24 hours in some parts of the UK than fell during the whole of July, forecasters have warned.
August will get off to a chilly, bright start in the North with rain over significant parts of the South feeding into a changeable seven days, the Met Office said.
The mixed forecast comes one day after a water spout was spotted at Thorpeness descending from dark clouds looming over the Suffolk coastline.
Pictures captured by onlookers show the swirling funnel spinning through the waves. Forming over water, the feature is rarely spotted as the tornado appears over the sea, with around 100 of them occurring annually.
A Met Office forecaster said: “July was obviously very, very dry, across parts of south-west Britain in particular, so there is a good chance we could see more rain across parts of the South West in the next 24 hours on Monday than we’ve seen in the entire month.
“It will be a real topsy-turvy week - no two days quite the same. But in the next five to seven days we will all see some rain at times - useful rain for those who have got parched gardens; obviously not great for those under canvas or trying to enjoy the beach.”
While sun-lovers hoping for a lengthy heatwave in the next fortnight may be disappointed, the month should avoid being a washout.
Moving into the second week of August, the further north-west parts of the UK the greater chance of seeing rain and stronger winds, while the South East will be generally a bit drier with a greater chance of seeing more prolonged periods of sunshine and high temperatures.
People can expect temperatures of low 20Cs in the South, and high teens in the North - “not a washout by any means, but again not exactly blazing summer either”, the Met Office said.
The best chance for a settled, warm period will be early on in the second half of August, particularly in the South, but the Met Office warned there was “certainly no strong signal for any prolonged period of hot weather” at the moment.
“We saw how quickly in July it can turn hot for a day and then be all gone the next; it’s not completely ruling out some hot summer weather but it’s unlikely to be long-lived event if it was to come off,” the forecaster added.
The Isle of Wight saw its driest July on records, with only 1mm (0.04in) of rain falling over the month.
However, the start of August brings a change in weather, with up to 20mm (0.8in) of rain expected over the next 24 hours.
A second Met Office forecaster, Simon Partridge, said: “According to records it is certainly the driest July on the Isle, certainly at St Catherine’s Point.
“But there is rain on its way - a weak little band of rain that has already crossed most of Cornwall and Devon.”
Meanwhile, Coral has cut the odds on this August being the hottest on record from 5-1 to 3-1, amid a flurry of bets that Britain will bask in a heatwave before the month is out.
This morning’s Met Office forecast for Portsmouth was: ‘Today: After a dry start with some sunny spells, cloud will increase during the morning with the odd light shower possible. More general rain will spread east during the afternoon, becoming more persistent and locally heavy in the west by evening. Maximum Temperature 20 °C.
‘Tonight: Cloudy overnight with outbreaks of rain, heavy in places, but tending to become lighter and more patchy by morning away from southern coastal areas. Minimum Temperature 13 °C.
‘Tuesday: Rain and drizzle dying out from the west during the day with some bright or sunny intervals later. Breezy at times, especially in the south, but feeling warm and humid. Maximum Temperature 23 °C.
‘Outlook for Wednesday to Friday: Any early rain in the south soon clearing on Wednesday morning, otherwise bright or sunny intervals and scattered showers through to Friday. Windy at first, but winds easing by Friday.’