Red extreme heat warning takes effect in UK as record temperatures expected

Red Extreme Heat Warning issued by the UK's weather service Met Office came into effect on Wednesday morning, with expected record temperatures for June.

Met Office issued the warning on Monday to come into effect from Wednesday and Thursday, "with June's all-time daily record temperature forecast to be broken."

Temperatures are expected to climb to at least 39C (102.2F) during the day in some parts of the UK.

According to Sky News, hundreds of schools have been closed in England and Wales, while widespread disruption has hit rail services amid the heat wave.

Transport operators have urged passengers to avoid travelling where possible to reduce the risk of heat-related disruptions, such as buckled rails and sagging overhead power lines.

The British grid operator, the National Energy System Operator (NESO), has called for increased power generation after issuing an electricity margin notice on Tuesday night.

"Our forecasts are showing tight margins on the electricity system for tomorrow evening (Wednesday)," a NESO spokesperson said, adding: "This is due to the impact of extremely high temperatures affecting Great Britain and the continent, as well as low wind."

The spokesperson also reaffirmed that the warning does not mean electricity supply is at risk.