Wild weather is as much a part of the Glastonbury experience as long drops, stone circles and sleep deprivation.
Leading up to the event are weeks of will-it, won't-it weather reports that whiplash between warning festival-goers to bring their wellies and their factor 50.
This year looks set for periods of rain but also dry spells and sunshine. However, after a period of heavy rain in the run-up to the festival, the ground could be worryingly wet when campers arrive to pitch their tents on Wednesday.
Of the 33 festivals to date, only eight have been completely rain-free. Glastonbury's sodden reputation was sealed in 1997 and 1998 as the 800-acre site quickly became a quagmire.
The arrival of BBC's camera crews for the first time burned the mudbaths into the public memory, gladly capturing every sludge-soaked camper and flooded field and earning 1997 the grandiose title "The Year Of Mud".
The result was devastating, with slots being cancelled as stages became waterlogged and the Dance Tent almost disappearing in the muck.
The festival rivalled Genesis' biblical flood in 2005 when two months' worth of rain fell in just two hours on the site.
Hundreds of tents were washed away, stricken campers were trapped in chest-high water, campervans were bogged down, and helicopters bringing acts in to perform could barely land.
Power outages caused delays and cancellations to the schedule as thunder provided its own soundtrack to the festival's 35th anniversary.
The dire situation was echoed just two years later, despite Michael Eavis spending a reported £750,000 on flood defences. It did not deter the 135,000 attendees, who frolicked in the mud to headliners Arctic Monkeys, The Killers and The Who.
In 2010, dehydration was the order of the day, with a heat-wave that saw the mercury topping 28 degrees Celsius.
Medical staff reported that more than 2,100 people had come in for treatment by Saturday evening alone, mainly for heat-related issues.
Luckily foresight saw the festival install a second million-litre water reservoir to keep the campers partying through the sunshine.