North America’s eastern seaboard and the Gulf of Mexico face increased threats from storms in the next three months, according to Guy Carpenter.

The reinsurance broker says unstable air and rising water temperatures are creating the right conditions for hurricanes to develop.

“From August through October, weather disturbances known as African easterly waves will leave the coast of Africa on a frequent basis,” the company says in a briefing note.

“It is not unknown for these waves to remain intact as they cross the Atlantic, in a fairly weak state, developing into major hurricanes.”

That is how Hurricane Andrew developed in 1992, in what was otherwise a quiet storm season.

“While tropical cyclone activity may be reduced, storms that develop in the west Atlantic and Gulf pose a higher threat to land, including the coastal US and Canadian maritimes,” Guy Carpenter says.

“It is impossible to rule out the landfall of a major hurricane in the Atlantic basin for the 2012 season.”

So far this year there have been two named storms in May – the first time this has happened since 1908 – four in June and none since.