The UK is very hot. An RSPCA worker, Chris O'Brien, locked himself in a car to show how bad it is for dogs. He did this for 25 minutes.

Chris used a thermometer and a stopwatch. He filmed himself and saw the temperature go up fast. It started at 23.3C.

After 10 minutes, it was 43.6C. Chris felt his heart beating fast and his breathing getting harder.

Chris said, 'I am very hot. I don't know how to explain it.'

Chris sweated a lot. Dogs get hotter than humans because they cool down differently.

Chris knew he could leave the car, but dogs don't understand that. They get very upset.

After 15 minutes, it was 48.8C. Then it went over 50C.

Chris said, 'Everything is boiling. I don't know how a dog would feel.'

After 25 minutes, it was 57.1C.

Chris said, 'This is very dangerous. Don't leave dogs in hot cars.'

The UK will be hot again. Temperatures will go over 30C.

The RSPCA says don't leave dogs in cars, even for a few minutes.

Dogs can't cool down like humans. They get heatstroke easily.

If you see a dog in a hot car, call 999. It can be life-threatening.