Last month was 0.95C warmer than the 20th century average for July, meteorologists said.
The part-time worker was rehearsing with other staff members when he fell ill and lost consciousness at around 7:30pm.
Forecasters said parts of the North West had seen 40mm to 50mm of rain in 24 hours.
Metropolitan Police received a report of a body sighted in the water by Canary Wharf, east London on Thursday night.
Strong sunshine allowing temperatures to rapidly rise on Thursday.
Temperatures couldn't quite climb to 39C.
As the UK is bracing itself for what could be its hottest ever day, authorities warn of the dangers of cooling off in water.
If temperatures stay high in the same spots for three consecutive days, the Met Office deems it a heatwave.
As the mercury rose, beaches and swimming pools became busy with those looking for a way to beat the heat.
Day by day the temperature will continue to rise