The unseasonal warm weather means raves may still take place, say the police.
And the force has urged people to be on the lookout for suspicious activity.
Raves can not only lead to noise and nuisance but are also more difficult to clear once they are established.
A Northants Police spokesman said: “We can nip illegal raves in the bud and stop them from taking place if we have reliable information.
“We are often alerted to raves by local people calling us to complain about a sudden increase in traffic and anti-social behaviour as people arrive at a venue, which we would encourage people to do.
“In many cases those people who are looking to set up a rave will visit the proposed site a couple of days before the event and I would urge anyone who spots any suspicious activity in their village, along a country road or around farmland to please let us know.”
Signs a rave is being planned can include flattened or disturbed hedgerows, cropped bolts on a gate and people in cars stopping to look at a field or climbing over a fence into a field.
Members of the public can report suspicious activity at www.northants.police.uk or by calling 101.