With top temperatures predicted to linger around the 30-degree mark, operators of Lake Keepit, Chaffey, Copeton and Glenbawn dams are expecting an influx of holidaymakers and day-trippers.

Lake Keepit manager Kerry Lloyd said the October long weekend was the park's second busiest period of the year, behind only the Easter long weekend.

"Most of the people seem to be camping this year, although all our cabins and roofed accommodation is also full," Mrs Lloyd said.

She said while the dam was only at 13 per cent, it was still "very useable" for boating, skiing, fishing, kayaking and swimming.

"The main thing that we ask is for people to use common sense and not go too close to the edges," Mrs Lloyd said.

"State Water is releasing water for cotton farmers and a few people have been getting bogged.

"But it's going to be an absolutely beautiful weekend out here and we're very excited."

Manilla's Jenny Ainsworth spent yesterday at the park with her partner and children and said the conditions were just "magic".

"We had an absolute ball," Ms Ainsworth said.

"The water temperature was great for swimming and the kids especially loved it."

The park is open from 8am to 5pm over the three days. Chaffey Dam operates on a "first come, first in" honesty-box system for campers, with barbecues and toilet facilities provided.

Copeton Dam, 50km from Inverell, holds three times the volume of Sydney Harbour and is a fishermen's haven, loaded with cod, yellowbelly, silver perch, catfish and redfin.

It offers a function centre, bunkhouse, powered sites, cabins and bush camping.