Extreme heatwaves spread as US told to expect hot and smoky summer

South Florida's outdoor workers demand better working conditions and protection against the extreme heat during the 'Qué Calor' demonstration in Miami. Photograph: Cristóbal Herrera/EPA

Extreme heatwaves are continuing to spread across the country as meteorologists warn Americans to prepare for a hot and smoky summer. With the 235 out-of-control Canadian wildfires showing no signs of dying down, smoke has drifted south into the US and shrouded multiple cities including Chicago and Detroit in a thick haze.

There are no signs of the relief coming for the next week or longer, according to the National Oceanic and Atmospheric Administration’s Weather Prediction Center.