London was, then, a dirty, smelly city well before the summer of 1858, with poor sanitation and a filthy main river running through it. So the last thing Londoners needed was a heatwave. But that’s exactly what they got. In June of that year he temperatures in the capital averaged 34-36 °C (93-97 °F) in the shade, rising to 48 °C (118 °F) in the sun. far from being pleasant, this made things truly unbearable. Indeed, it was said that you could smell the foulness of the Thames more than 8 miles away!