Glastonbury 2014: Festival Goers Arrive Under A Grey Sky Ahead Of Heavy Rain Forecast For The Start Of This Year's Music Festival (FIRST PICS)

Glastonbury 2014 is officially open with thousands of music lovers beginning to stream through the gates of Worthy Farm in Somerset for this year's festival.

And despite a grey sky, there hasn't been any need for wellies - yet - with no rain falling at the site so far.

However, the outlook isn't looking good with weather forecasters predicting heavy downpours on Thursday, and a potential mudbath on Friday.

More rain is expected on Saturday and Sunday.

"But by Friday it looks as though the rain, some of it quite heavy, will arrive."

Emily Eavis, who organises the festival with her father Michael, took to Twitter to announce that this year's Glastonbury was officially open.

"The gates are open! Welcome to Glastonbury Festival 2014," she tweeted.

The first big acts won't be performing until Friday, when the likes of Blondie, Lily Allen, Arcade Fire and Paolo Nutini will all take to one of the stages.

Other acts scheduled to play to over 200,000 punters over the weekend include Robert Plant, Haim, Goldfrapp, London Grammar, Ellie Goulding, Metallica, Lana Del Ray, Ed Sheeran and country music legend Dolly Parton.

Glastonbury 2014

Glastonbury 2014