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WASHINGTON - After a couple years of wild, deadly and costly weather, the United States is mostly getting a lucky break this year. So far.

Hurricane and tornado activity in 2013 has been flirting with record low levels, while heat waves are fewer and milder than last year.

Meteorologists credit a combination of luck, shifts in the high-altitude jet stream, and African winds and dust.

So far, there have been eight tropical storms. Not one has developed into a hurricane, though Tropical Storm Humberto - way out in the Atlantic off Africa - is likely to become one soon.

If Humberto stays a tropical storm through Wednesday morning, 2013 will set the record for latest first hurricane of a season.

SETH BORENSTEIN, AP Science Writer