This year's Glastonbury Festival could be hit by "heavy showers and thunderstorms" between Friday and Sunday, according to the Met Office.
After a break of three years due to coronavirus, the festival opens its doors to ticket-holders tomorrow morning - and more than 200,000 people are expected to attend between then and Monday.
While temperatures in the high 20s are expected in the first couple of days, the weather is expected to turn sour by the time the weekend arrives.
"You should plan for both sunhats and raincoats for this year's festival," said Helen Caughey, the Met Office's deputy meteorologist.
"There will be plenty of sunshine on Wednesday across the South West, although there could be a bit more cloud later in the day, and temperatures will reach 26C or 27C. The dry, sunny and warm theme will continue through Thursday.
"However, from Friday onwards the weather will become more unsettled. There is a risk of heavy showers and thunderstorms in the Glastonbury area on both Friday and Saturday, although these should be quick moving, some surface water might accumulate at times. Temperatures will start to dip as we go through the end of the week returning to near normal for the time of year, with highs likely around 18-20C.
"Sunday is expected to be mostly dry and bright at first but with showers once again developing through the morning, some of which could be heavy, and possibly thundery. The unsettled pattern is expected to continue to dominate into the start of next week."