In Pictures: Sunny start to Wimbledon as England enjoys one of hottest June days
A temperature of 29.7C was recorded at Kew Gardens, setting a provisional record for the hottest start to the tennis championships.
Parts of England and Wales were expected to be hotter that some Caribbean countries on Monday, with forecasters predicting highs of 34C.
The sweltering heat means Monday is set to be one of the hottest June days ever, with UK temperatures for the month only surpassing 34C in only three years since 1960.
Sports fans basked in the sunshine as Wimbledon got under way, with it hottest opening day ever. A temperature of 29.7C was recorded at the nearby Kew Gardens, setting a provisional record for the hottest start to the championships.
At Worthy Farm in Somerset, the clean-up operation got under way following the Glastonbury Festival.
As the final festivalgoers departed with their belongings, volunteers arrived on site to begin clearing away litter and leftover items.
Across Europe, the heatwave continued, pushing countries like Italy, Spain and Greece above 40C.
However, scientists have warned that heatwaves are becoming more frequent with climate change – and hot spells earlier in the summer are particularly dangerous.
In Scotland, firefighters battled wildfires as experts warned that higher temperatures and droughts increase the risk of wildfires.