BRITAIN is set to be as hot as Rio de Janeiro today before the temperature drops tomorrow and rain hits.
The Met Office says the temperature in London will reach 24C today - and could climb as high as 25C.
That would make the capital as warm as holiday hotspot Rio de Janeiro - which is also forecast to be 24C - albeit it is the winter in the southern hemisphere.
It comes after the UK basked in another hot day on Sunday, the joint hottest of the year so far.
The mercury rose to 32.2C in Coningsby, Lincolnshire, matching this year's record which was set on June 10 in Chertsey, Surrey.
However conditions are now expected to cool this week with fresher air expected, particularly in the South East.
Read more News
Met Office meteorologist Jonathan Vautrey said: "A lot of morning sunshine to kick us off in the new working week.
"But those showers in the west will gradually filter their way in and further ones bubbling up across parts of northern England and and Northern Ireland in particular.
"Some of those showers could be heavy in nature and you might see an isolated thunderstorm as well, but they'll be some sunshine in between those scattered showers.
"For Wales, central and southern areas of England are more likely to stay driest throughout the day with some sunny spells.
Most read in The Sun
"The sunshine could turn hazy particularly for southern Wales and south-west England as a wispy cloud pushes its way in."
Forecasters say it will be less humid and the cooler weather will be a relief to some, particularly with more comfortable temperatures of 13C at night.
It is expected to be dry throughout the evening with some late sunshine, before cloud pushes in from the west around dawn.
Tuesday will see cloud thickening and rain pushing in from the west over Ireland with winds also strengthening.
The rain will keep moving west with heavy bursts expected over western Scotland, north-west England and northern Wales.
The weather will be mostly dry and cloudy on Wednesday, before a band of heavier rain pushes through later in the evening.