At least 42 people have died in a heatwave that has gripped America's East Coast, according to reports.

They included a four-month old Indiana girl who police say was left in a car outside her home in Greenfield, about 25 miles east of Indianapolis, "for an extended period" in temperatures above 38C (100F).

Crops shrivelled, roads melted and lakes parched from Chicago to New York in the blistering heat which came just a week after storms battered the region, causing outages for many.

A high number of the victims were said to be elderly residents stuck in their homes without air conditioning because of the power cuts.

Ten deaths in Chicago were blamed on the heat, and at least 10 each in Virginia and Maryland. Wisconsin, Ohio and Pennsylvania each counted three deaths, while there were two in Tennessee.

Triple-digit temperatures have tied or broken nearly 3,400 maximum and minimum records across the US this month so far, according to the National Oceanic and Atmospheric Association.

However cooler temperatures are expected with a further bout of storms predicted.