“Impactful” thunderstorms are predicted to cause travel disruption as the first campers make their way towards Glastonbury Festival on Tuesday, the Met Office said.
The forecaster said thunderstorms in Devon and Cornwall and eastern areas of England could cause “potential transport disruption” ahead of festival gates opening on Wednesday.
Thundery downpours are expected on Tuesday in areas of Devon and Cornwall, with up to 50mm of rain predicted to fall in three hours. These showers will stick around until the early evening on Tuesday.
Meanwhile, a yellow thunderstorm warning covering eastern areas from London to Hull will likely see “severe thunderstorms throughout the day”, with possible hail and up to 40mm of rain predicted to fall in an hour.
Met Office spokesman Oli Claydon said: “Where thunderstorms do pop up, these have the potential to be impactful. There could potentially be disruption to rail services with lightning strikes.
“What’s causing the thunderstorms is a warm humid plume of air moving up from the South north-eastwards.”
However, the festival itself should avoid the worst of the weather.
He said: “There could be some showers around for the first couple of days, especially during the set up today and Wednesday, but there will be dry spells as well.”
This should mean festivalgoers avoid the infamous Glastonbury mud.
Despite showers, temperatures are expected to remain warm at 22C on Wednesday and Thursday.
Towards the weekend, the rain is expected to clear, making way for dryer and brighter conditions with highs of 26C expected on Sunday for Sir Elton John’s headline performance.
Mr Claydon said: “For people sleeping in tents, temperatures will remain in the mid-teens at night, so relatively warm.
“Be prepared for all weather types, with showers possible early in the week with warm weather taking over for the weekend.”
The festival will see Arctic Monkeys, Guns N’ Roses and Sir Elton headline the Pyramid Stage after the music kicks off on Friday.