But while zoo animals munched on frozen treats and office workers topped up their tan, Public Health England warned people not to get too blasé about the heat, as emergency calls soared.
London Ambulance Service reported 300 more calls than normal from people who have breathing conditions and had forgotten to stay hydrated.
The RSPCA also reported a spike in calls from those worried about dogs and cats left in hot cars and conservatories.
Companies and news organisations also clamoured to capitalise on the weather with some running a live blog or offering fashion tips and reminders about ice cream sales.
However, the heat is expected to turn to thunderstorms later in the week, the Met Office reported.
