Police across Devon and Cornwall are on rave alert to prevent illegal parties.
Hundreds of people invaded Smeatharpe airfield in 2002
Officers said the cancellation of both Glastonbury and the alternative Lost Vagueness festival near Exeter raised the possibility of sites being set up.
The Smeatharpe airfield in Devon has experienced problems in the past and in May this year 2,500 people set up an illegal rave near Camelford, Cornwall.
Police said they were working with other forces and wanted people to look out for sites appearing overnight.
Devon and Cornwall Police said there had been no specific intelligence that any raves were planned over the bank holiday weekend.
The force said it just wanted to ensure it could deal with any illegal raves quickly and with the minimum disruption for locals should they arise.
Ch Insp Richard Baker, of the force's contingency planning unit, said: "By letting us know if they think an illegal rave is starting, or if they believe people have been visiting land to see if is suitable for such an event, the public can help us get ahead of the game and prevent the disruption caused once a site is established."
Police said officers' concerns also included the safety of those attending any gatherings.
The force said new powers meant officers could seize equipment and stop events, and that they would deal robustly with any offences found.