Extra staff are being drafted in by Avon and Somerset Police to deal with expected problems around Halloween.
More patrols are planned for 31 October to target anti-social behaviour hot spots, with the number of 999 calls expected "to soar".
Supt Chris Weigold said: "Calls build up gradually during the day, peaking during the late evening".
"On an average day we receive 776 calls via the 999 system but on 31 October this was up to 1338 last year."
He added: "This doesn't include the additional demand of alarm activations and calls routed from the other emergency services."