Brutal heatwave cooks US south-west, an early sign of sizzling summer ahead

Millions of Americans are sweltering as experts warn early heat could herald next record-smashing summer

With the official start of summer still weeks away, a record-setting heatwave is cooking the south-western US, causing dangerous conditions far earlier than normal.

More than 34 million people were under heat alerts on Thursday afternoon, as warnings were issued from the southern tip of Texas across Arizona and Nevada, and up through the center of California to the northern part of the state.