Experts say 2009 already has been proved a dangerous year for lightning strikes in the United States and warn the worst may be yet to come.

National Weather Service lightning expert John Jensenius said 11 people have been killed in the United States by lighning strikes just this month as the particularly dangerous summer months get under way, ABC News reported Monday.

"Last year was an exceptionally good year for not having fatalities. This year is starting out as an exceptionally bad year, compared to the past five years," Jensenius said. "It's been every day or almost every other day in June."

The current June tally of lightning fatalities falls short of the 30-year average for the month of 13 deaths, but marks a increase from the June 2008 total of eight fatalities nationwide.

Nearly 60 of the more than 400 people struck by lighting in the United States annually die, weather service estimates show.

Lightning expert Mary Ann Cooper of the University of Illinois-Chicago told ABC News there is a simple way to limit such deaths.

"When thunder roars, go indoors," she said. "No place outside is safe when thunderstorms are in the area."

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