Bookmaker Ladbrokes said a slumping slot machines market, fewer football punters and the recent heatwave, hurt trading as half-year profits dived almost 50%.
Shares in the bookie came under pressure after it warned trading had failed to improve since the first half, with July footfall 15% lower as soaring temperatures kept customers out of its shops.
It has also been squeezed by more people backing winning favourites, as hard ground meant fewer horses per race.
The group is the latest company to report heatstroke after Newcastle-based bakery chain Greggs revealed earlier this week it was left nursing a £2m hit to profits from slumping pasty and cold drink sales.
Ladbrokes said the gaming machines market has slowed more than feared, with intense competition adding to the woes, almost halving pre-tax profits for the first six months of the year to £55.1m from £106.9m.
Gaming machine revenues have been a big driver of growth in the industry, but Ladbrokes has seen rates slow as the market becomes more competitive.
It has also been hit by a new 20% machine gaming duty this year.