US President Joe Biden has announced a 2.3 billion dollar fund to help build infrastructure that can withstand extreme weather and natural disasters.

Biden spoke in Massachusetts as a heatwave brings extreme weather to Europe and North America.

But, he stopped short of formally declaring a climate emergency, which would grant him further powers.

Millions of people in the US, across more than two dozen states, are living under heat warnings this week.

He said the funding would go to expanding flood control, shoring up utilities, retrofitting buildings, and helping families pay for heating and cooling costs.

The money comes from an existing Federal Emergency Management Agency budget and will be prioritised for disadvantaged communities.

It includes 385-million dollars to help states fund air conditioning units in homes and community cooling centres.