An inscription carved into a block of Egyptian stone 3,500 years ago is likely one of the globe's most ancient weather reports, researchers say.

While there's no way to know if it was any more accurate that modern forecasters' attempts, it does give new clues into the timeline of certain occurrences in the Middle East millennia ago, experts at the University of Chicago say.

A translation of the 40 lines of text chiseled into a six-foot-tall black of calcite known as the Tempest Stela speaks of darkness, rain and "the sky being in storm without cessation, louder than the cries of the masses," they said.

The darkness and unusual weather described in the inscription were likely caused by a massive volcanic eruption on the Mediterranean island of Thera, now called Santorini, University of Chicago researchers Nadine Moeller and Robert Ritner report in the Journal of Near Eastern Studies.

Because volcano eruptions can impact weather over a large area, the Tera eruption probably would have resulted in significant climate effects in Egypt, they said.

They suggest the finding could change our understanding of a crucial time in history when empires in the Bronze Age were realigning.

The Tempest Stela has been dated to the first pharaoh of Egypt's 18th Dynasty, Ahmose, at the beginning of what's known as the New Kingdom when the empire's power was at its highest.

The new inscription translation suggests Ahmose ruled at a period closer to the eruption of Thera than previously believed, so the correct date of both the stela and the reign of the pharaoh, previously considered as around 1550 B.C., might be 30 or even 50 years earlier.

Radiocarbon testing on wood buried under volcanic ash from the Thera event puts the date for the eruption closer to 621-1605 B.C., the researchers said.

"This is important to scholars of the ancient Near East and eastern Mediterranean, generally because the chronology that archaeologists use is based on the lists of Egyptian pharaohs, and this new information could adjust those dates," Moeller says.

The inscription on the stone says Ahmose himself witnessed the disaster, which resulted in dead bodies floating down the Nile River like "skiffs of papyrus."

Significantly, the inscription refers to events at both Egypt's delta region adjacent to the Mediterranean and areas further south on the Nile.

"This was clearly a major storm, and different from the kinds of heavy rains that Egypt periodically receives," more evidence of a major volcanic event affecting weather over a large region, Ritner said.