Another heatwave hits US and Canada

A heatwave bringing high temperatures and poor air quality has affected large areas in the US and Canada, continuing from Tuesday into Wednesday.

• Millions of residents are under heat advisories in Boston, New York City, Philadelphia, and Buffalo through Wednesday.
• All-time temperature records were broken in parts of Montana and Utah as the heat shifted eastward.
• Forecasts predict temperatures reaching 97F in Chicago, 100F in New York, and 102F in Washington DC on Wednesday.
• A cold front is expected to bring lower temperatures and the threat of severe thunderstorms in central and eastern Canada and New England by the weekend.