The latest Met Office forecast shows a high pressure system will be in place over the next week, ensuring conditions across Britain remain sunny and warm with little chance of rain or wind.
Greg Dewhurst from the Met Office said both sites of the festival would see fine summery weather throughout the long weekend.
“Sunshine amounts will vary day by day, but lots of bright and sunny spells,” he said.
“Temperature wise we’re looking at Leeds around about 20 Celsius each day and Reading around similar values, 20 or 21 each day. There will be variable amounts of cloud but a dry picture throughout.”
The twin festivals, which sees the headliners performs at both sites across the weekend, were cancelled last year due to the coronavirus pandemic.
Many of the acts booked for last year’s festivals are returning for 2021, including Stormzy and Liam Gallagher. Rounding out the bill are American rapper Post Malone, dance duo Disclosure, and rock band Queens of the Stone Age.
The festivals are among the UK’s biggest outdoor events, and will be perhaps the largest music festivals in the country this year as Glastonbury decided to cancel for a second year running.
Elsewhere, much of Britain will enjoy similarly good weather to the festival-goers. Mr Dewhurst said there was a very low chance of a few isolated showers in the far south-east of England on Saturday, but generally the whole country will be dry with sunny spells, with the best of the sunshine in westerly areas.
“There are signs initially it might start to become a little bit more unsettled as the week goes on, but the latest models generally keep it on the settled side for most of next week as well,” he added.
“Perhaps it is more likely for the northern parts of the UK by the end of next week might start to see sort of some wetter and windier weather, but it looks like much of next week staying dry as well.”
UV levels will remain moderate as the sun begins to lose its strength towards the end of the summer.
However, any prolonged spells of sunshine could still pose a risk of higher levels, both at Reading and Leeds, so revellers should “definitely have your suncream handy”, he said.