Oil refineries across the country have been plagued by a record number of fires, power failures, leaks, spills and breakdowns this year, causing dozens of them to shut down temporarily or trim production. The disruptions are helping to drive gasoline prices to highs not seen since last summer’s records.

These mechanical breakdowns, which one analyst likened to an “invisible hurricane,” have created a bottleneck in domestic energy supplies, helping to push up gasoline prices 50 cents this year to well above $3 a gallon. A third of the country’s 150 refineries have reported disruptions to their operations since the beginning of the year, a record according to analysts.

There have been blazes at refineries in Louisiana, Texas, Indiana and California, some of them caused by lightning strikes. Plants have suffered power losses that disrupted operations; a midsize refinery in Kansas was flooded by torrential rains last month.

American refiners are running roughly 5 percent below their normal levels at this time of the year.

“You have a system that is taxed to the limit,” said Adam Robinson, an energy research analyst at Lehman Brothers. “This is what happens when spare capacity is eroded.”