LONDON/PARIS: British and French authorities have warned people to stay safe as an early summer heat wave brings unusually high temperatures to northern Europe.

According to the UK's Met Office, temperatures in eastern England reached 34°C (93°F) on June 21, which is around 12°C (22°F) hotter than usual for this time of year. In France, it's expected to be even warmer, with some areas in the west and south likely to hit 38°C (100°F).

The UK Health Security Agency (UKHSA) and the Met Office have issued an amber heat health alert across all of England until the morning of June 23. This means the heat could pose health risks, especially for people over 65 and those with heart or lung problems.

Dr. Agostinho Sousa from UKHSA said heat can seriously affect health, especially for older adults and people with existing medical conditions. He advised checking on vulnerable people and taking sensible steps to stay safe in the sun.

In France, the national weather service, Meteo France, also warned that the high temperatures could affect everyone, even healthy people.

The heat wave has already affected events. At the Paris Air Show earlier this week, visitors tried to escape the sun by standing in the shade of a large Boeing 777 as temperatures reached the low 30s°C (mid-80s°F).

June 21 was the hottest day in the UK, with slightly cooler weather the next day and a return to normal temperatures next week.

In the Netherlands, Amsterdam's 750th birthday event has added extra water stations and limited the number of tickets due to concerns about the heat. Officials said the ring road, where the event is held, could become even hotter due to the asphalt surface.

Other events in the Netherlands have been cancelled, including marathons and concerts. The Philzuid symphony orchestra cancelled outdoor performances in Eindhoven to protect their instruments from the heat.

Experts say these heat warnings are happening more often because of global warming. New research from the UK Met Office shows that climate change is making extreme heat more likely. The chance of temperatures above 40°C (104°F) in the UK is now over 20 times higher than it was in the 1960s.

People are being urged to drink plenty of water, stay in the shade, and avoid going out during the hottest parts of the day.