Britvic says that the recent shortage of CO2 gas has impacted on its ability to make the most of the hot weather.
The soft drinks maker reported a 3.4% rise in third quarter sales to £366.9m, compared to 4.5% growth in the same quarter last year.
Britvic chief executive Simon Litherland, said: "Whilst the industry-wide shortage of carbon dioxide held back our ability to fully capitalise on the exceptional weather in GB and Ireland, we leveraged the breadth and strength of our portfolio to moderate the impact."
Commenting on the CO2 shortage, Britvic said: "To ensure continuity of supply across all trading channels, we temporarily scaled back our promotional activity and reallocated some of our secondary feature space to stills.
"Supply has now normalised, enabling us to start rebuilding stock levels and gradually reintroduce promotions."