The warnings come after large parties and a couch fire in Hyde St on Saturday night led to the arrest of four men.
Police were called to the notorious student hot spot just before 11pm to clear partygoers and allow firefighters to extinguish the blaze in the middle of the street, Senior Sergeant Dave Scott said.
Of the four men arrested, one was a student. The 19-year-old has been charged with lighting a fire and now faces an uncertain academic future.
The others arrested included an 18-year-old electrician, of Dunedin, charged with using offensive language, a 17-year-old labourer, also of Dunedin, charged with obstruction, and a 19-year-old unemployed Gore man, charged with disorderly behaviour.
''Any congregation in the student area always points to the involvement of students but it doesn't mean the students are the ones causing the issues. However, the fire lighter on this occasion was a student and that is disappointing,'' Snr Sgt Scott said.
Last year, police, in consultation with the University of Otago, introduced a no-diversion policy for any offence involving a fire.
''That sends a pretty strong message to anyone lighting fires, particularly in the north area, that you won't be given a slap on the hand with a wet bus ticket; you will be off to the court to explain to the judge.''
Fires tied up emergency services' resources and ''potentially it can turn quite serious, and it is luck rather than anything else that one of these fires did not catch on to a house''.
''They are putting their futures at risk by one stupid night on the raspberries.''
Dunedin police alcohol harm reduction officer Sergeant Ian Paulin said students dealt with by police would be referred to the proctor.
''If you are arrested for an alcohol-related event, then you will be fronting up in front of the proctor, first thing in the ... morning,'' Sgt Paulin said.
This would probably result in expulsion if a student was involved in lighting a fire.
''The message is, if you want to stay at university, you don't go anywhere near a couch fire.''
Police would have additional staff rostered on during O-Week and would carry out increased patrolling to make sure people were safe and to enforce the central city liquor ban. Breaches of the liquor ban could result in an infringement fine.
Police would also be visiting licensed premises to ensure they were complying with regulations in relation to intoxicated or under-age patrons.
Safe drinking
Police tips for having a good time during O-Week
• If you are going to be drinking alcohol, make a plan before you leave home about how you are going to get home safely.
• Share a cab or walk home in a group.
• Look after your mates - if your friend has had too much to drink, keep an eye on them and look after them.
• Don't let your friends wander off by themselves. Stick together.
• Don't drink and drive - it puts your life, your friends' lives and the lives of others at risk.