Wednesday will start off with some showers in parts of Wales, western England, Northern Ireland and Scotland.
The heaviest rain is likely to be in Scotland, where it will be thundery at times with downpours.
Meteorologist Matt Terry, who presented the BBC Breakfast weather report from Tatton Park in Cheshire, England, told viewers rain was a “hot topic”.
He said: “You could see showers across some western parts of the UK, more especially central, southern Scotland.
“There are a few heavier ones to come here through the morning and into the afternoon and the odd one will popping up in Northern Ireland too.”
For the vast majority of the UK it is going to remain dry this morning with sunny spells to the east and warm weather.
As the afternoon approaches most areas in Britain will see a rise in temperatures, but as the heat levels start to increase a few shower clouds will develop again.
Northern and western counties are going to bare the brunt of the wet weather, meanwhile there will be a downpour in northern and southern parts of Scotland.
Much of eastern England and the south east will stay dry and be warmer than previous days with London expected to reach 26 degrees Celsius.
Evening showers in western and northern areas will clear tonight to leave some areas dry, however, some patches of mist to develop overnight.
Tomorrow to be sunny with lots of sunshine around, although a weather system will begin to increase the breeze to western Scotland and Northern Ireland.
It could also bring a substantial amount of rain across the north and west, but it will weaken as it continues to move southwards.
Thursday is going to be a much hotter day with Birmingham, Hull, Norwich, London and Cardiff all topping 24 degrees Celsius.
Cooler on Friday in Scotland, northern Ireland, northern England and Wales. There is also the possibility of some thundery rain moving from the near continent into the south east.
A weather front could bring a bit of cloud and some patchy light rain to southern areas on Saturday.
As forecasters expect temperatures to pick up at the end of the week, bookmaker, Ladbrokes has cut odds on any part of the UK seeing temperatures of 35 degrees Celsius or higher before the month is out.
The bookies have slashed odds from 3/1 to just 5/2, while 1/5 says this goes down as the hottest summer on record.
It’s also now just a 4/6 chance a new 2018 high temperature record is set before the end of July.
Ladbrokes spokesperson Alex Apati said: “More hot spells have been forecast over the next few weeks and our odds have taken yet another hit as a result.”
BBC Breakfast airs weekdays on BBC One at 6am.
