Climate change was not the cause of the historic drought that plagued the U.S. Midwest last year, a federal government study indicates.

Although some have pointed the finger at climate change as being behind for the driest summer since records began to be kept more than 100 years go, a report released Thursday by the National Oceanographic and Atmospheric Administration said that was not the case, CNN reported.

Rather, the drought was the result of "a sequence of unfortunate events" that occurred suddenly, the report said, adding the circumstances were so unusual the drought could not have been predicted.

Drought occurred in six Plains states between last May and August because moist Gulf of Mexico air "failed to stream northward in late spring," and summer storms were few and brought little rainfall, the NOAA report said.

"Neither ocean states nor human-induced climate change, factors that can provide long-lead predictability, appeared to play significant roles in causing severe rainfall deficits over the major corn producing regions of central Great Plains," the report said.

The drought in Wyoming, Colorado, Kansas, Nebraska, South Dakota and North Dakota was the worst since record keeping began in 1895, study leader Martin Hoerling, a NOAA meteorologist, said.

"The event was rare, and we estimated maybe a once in a couple of hundred years event," he said.

"But for as extreme as it was, it didn't have any strong indications for early warning."