Brighton and Hove is expected to bask in a mini heatwave before a change in the weather at the weekend, according to forecasters.
And while temperatures are forecast to top their average for the time of year, pollen counts are also likely to continue to be very high.
The Met Office said: “There is a lot of speculation around the spell of hot weather expected towards the end of this week.
“It will become increasingly warm in the south as high pressure builds. This will bring settled conditions allowing temperatures to build day-on-day and for it to become warm, or even hot, for a time by Friday.”
The official forecaster’s deputy chief meteorologist Dan Rudman said: “Temperatures will rise through the week, becoming well above average by day by Friday when many parts of the southern half of the UK are likely to reach 30C or even 33C in isolated spots.
“This is the first spell of hot weather this year and it is still unusual for temperature to exceed these values in June.
“Many areas will also see some warm nights, with temperatures expected to be in the mid to high teens overnight.”
The top temperature in Brighton and Hove is expected to be 20C (68F), rising to 25C (77F) on Friday and 26C – or almost 79F – on Saturday.
But on Saturday (18 June), with a change in wind speed and direction expected, the temperature should feeler cooler than Friday.
The Met Office has localised definitions for a heatwave. Across Sussex, a heatwave is three consecutive days when the top temperature exceeds 27C – or almost 81F.
So while Brighton and Hove can expect warm and even hot weather – even for June – it won’t officially reach the threshold for a heatwave.
But changes in conditions overnight on Saturday mean that Sunday is likely to bring rain and possibly even thunder and lightning.