Harvester and Toby Carvery owner Mitchells & Butlers (LON:MAB) warned that wet weather would dampen full-year profits as it appointed a new chief executive.
M&B said annual results were likely to be at the bottom of market expectations, although they would still be ahead of last year's.
It said the UK eating and drinking out market had been subdued in the summer leading to a slight slowdown in the rate of sales growth, worsened by the wet weather.
The group also warned of "forthcoming cost pressures", although it voiced confidence that it would be able to overcome them.
M&B, which also owns Ember Inns and Miller & Carter, said chief operating officer Phil Urban would become chief executive from September 27.
Total sales growth for the first 50 weeks of the year was 7%, with like-for-like sales growth of 1%.
But while like-for-like food sales increased 2.5% in the 43 weeks to July 25, they fell 0.2% in the seven weeks to September 12.
He will replace Alistair Darby, who will quit the role the day before and leave the board and the company on that date.
Urban joined M&B in January 2015 as chief operating officer, and was previously managing director at Grosvenor Casinos, a division of Rank Group.
Prior to that, he was managing director for Whitbread's pub restaurant division, and for Scottish and Newcastle Retail's restaurants and accommodation division.
Chairman Bob Ivell said: "Phil is a strong leader with industry experience and a proven track record of operational delivery, who we are confident will build on the progress made under Alistair.
"The board recognises the significant contribution made by Alistair as chief executive over the past three years, is grateful to him for bringing the business to a stronger position and wishes him well."
Urban said: "Having worked in the business since the start of the year I have seen at first hand the exciting potential of the people, brands and estate of M&B and look forward to leading the business to further growth whilst meeting the challenges ahead."