Boris huffed and puffed and went in for a lot of spin, but eventually fizzled out without doing harm to anyone. But Bertha has meant business and blew up quite suddenly.

Boris and Bertha were some of the earliest tropical storms of the new hurricane season. Boris erupted in the Pacific way off the western coast of Mexico and died out without causing any damage. But Bertha has been something of a surprise. She formed last Thursday near the Cape Verde islands off the coast of West Africa, and set a new record for the farthest east that a tropical storm has formed in July, only a month into the hurricane season.

On Monday Bertha rapidly erupted into a powerful Category 3 hurricane, packing winds of 190km/h (120mph). The storm is moving across the mid-Atlantic and could threaten Bermuda by Saturday, although the US is expected to escape unscathed.

However, the appearance of the first Atlantic hurricane this early in the year is unusual. Forecasters are predicting a busy year for hurricanes and there are fears for a lot of activity by the peak of the season, around the middle of August to mid-October, when tropical sea temperatures have reached their warmest for the year, providing the fuel for hurricanes.