Glastonbury Festival 2011 revellers greeted by rain
Festivalgoers facing muddy conditions on the first day of Glastonbury have been warned to expect more heavy downpours over the next four days.
More than 137,000 people were due in total at the site at Worthy Farm, Pilton.
Police made 36 arrests for possession of drugs, theft and assault after the gates opened on Wednesday morning.
U2, Coldplay and Beyonce are the headline acts for the event, which sold out in four hours last October.
A spokesman for Avon and Somerset Police said the number of arrests made was higher than during the same time period last year but said reported crime had fallen from 50 to 41 cases this year. A quantity of drugs was seized.
Thirty of the arrests were for drug offences while the remainder were for assault, theft, and being drunk and disorderly.
Although some sunshine is forecast for Thursday, the mud is due to get worse with heavy showers expected on Friday.
BBC West's weatherman Ian Fergusson said festivalgoers could expect heavy downpours on Friday though the rain should ease up as the weekend progresses.
The best weather is expected on Sunday with temperatures expected to reach 22C, although conditions are predicted to be humid.
For the first year, a new route was being used by people travelling to the site by car, allowing drivers to be directed towards Wells on the A39 to try to avoid the traditionally-long queues on the A361 towards Pilton from Glastonbury.
Queues of traffic were reported for an hour earlier on the main festival routes, including the A303 at the Podimore Roundabout and the A37 at Pensford.
A Madame Tussauds waxwork of singer Beyonce was at London's Paddington Station as revellers boarded trains to the West Country.
This year, about 15,000 of the revellers are thought to be more than 50 years old, according to insurance company, Saga.
Pat Rogers, 61, has been to every Glastonbury Festival.
He said: "There's so many things to see and do for all ages, my father who's 91 who doesn't go down there is very interested, he watches a bit on the telly, I don't think we're too old."
Glastonbury organiser Michael Eavis said he thought this year's festival "moment" would be a tomato fight in his new "medieval bullring" Campo Pequeno, which has been made out of lockgates from canals in Somerset and Wiltshire.
Other new features this year include The Spirit Of '71 stage, featuring acts which played at one of the first Glastonbury festivals 40 years ago.
The festival features 60 official stages and there will be more than 2,200 performances, including speakers and poetry readings.
The site also has more than 3,200 toilets which will be serviced by a team of 300 during the event.
The annual festival will be taking a year off in 2012 to allow the dairy farm's land to rest.