Police in North Yorkshire have urged people from areas with the highest Covid-19 infection rates not to travel to the county in the October half-term.
Officers are also asking parents to make sure they know where their children are during the break.
The force said those in tier three areas such as South Yorkshire, Manchester and Lancashire should not travel for leisure reasons.
Supt Mike Walker said they were asking for help in dealing with Covid-19.
"North Yorkshire is notorious for providing a warm welcome to visitors," he said.
"But at the moment, we would ask residents from tier three locations to please stay in their own area and help us with the containment of this virus."
Officers said they had responded to several reports of young people being in breach of the "rule of six" in recent weeks, and that no enforcement action was needed.
But with the half-term break approaching, they are highlighting the threat these types of gatherings pose to public health.
Supt Walker said: "It's a trying time for everyone, including parents and children, but it's key that we remember the guidance and ensure that we don't have a momentary lapse in our resilience to beat this virus.
"I would ask parents and carers to speak to their young people and remind them about the importance of following the guidance over the school holidays."
North Yorkshire currently remains in tier one, although discussions are being held over a potential move to tier two so that it comes in line with other areas in the region.