Despite forecasts of an above-average Atlantic hurricane season,none of the seven tropical storms experienced so far this year havereached hurricane strength, making 2013 the first year in more thana decade to not have produced a landfall by August.

According to Claire Souch, vice president of model solutions atRMS, hurricanes have been unable to form so far in 2013 due tohigher-than-normal wind shear in the atmosphere, cooler seatemperatures in the eastern Atlantic, and sand and dust particlesfrom the Saharan air that have been pushed into the atmosphere,disrupting hurricanes that would normally be formed by tropicalwaves coming from western North Africa.

The Atlantic hurricane season has been relatively quiet, witheight tropical storms and no hurricanes. Last year at this timethere were 13 named storms and seven hurricanes.

Tropical Storm Humberto formed near the Cape Verde Islands onSept. 9 and was expected to strengthen into the first hurricane ofthe Atlantic storm season, but it is not expected to threaten theU.S.

The well-known hurricane forecasting team of Philip Klotzbachand William Gray at Colorado State University called for 18 namedstorms in the Atlantic this season, with eight hurricanes and threemajor hurricanes. Klotzbach told Reuters the duo would “back down from theprediction considerably” if they put out a mid-season update.

But forecasters still warn of complacency.

Last year, Superstorm Sandy, which caused more than $22 billionin insured losses as the second-costliest hurricane in U.S.history, occurred in late October.

RMS says September is the busiest month for hurricanes,averaging 2.1 each year, and predicts that if current windshearsettles, a significant hurricane event could still occur due towarmer sea surface temperatures.

“Models are currently forecasting significant developmentpotential for enhanced tropical storm development over the comingweeks, with an expected decrease in the inhibiting factors, makingconditions favorable for late-season development,” says Souch.

Humberto would be the latest date a hurricane has formed in theAtlantic during the hurricane season since Hurricane Gustav reached74 mph on Sept. 11, 2002.

The prior year Erin was the first storm to reach hurricanestatus on Sept. 9, which didn't stop the 2001 season from exceedingall forecasts with 15 named storms, nine hurricanes and four majorhurricanes. Nevertheless, the U.S. wasn't affected by anyhurricanes in 2001.