New Delhi (CNN) What is expected to be India's strongest tropical cyclone to make landfall in 20 years is barreling toward 100 million people on the country's east coast, prompting officials to begin emergency evacuations.

On Thursday, Tropical Cyclone Fani had strengthened significantly in the Bay of Bengal, with maximum sustained winds of 250 kilometers per hour (155 mph) and gusts of up to 305 kilometers per hour (190 mph), according to the Joint Typhoon Warning Center.

Fani, which is about 60 kilometers (38 miles) off the coast of Andhra Pradesh and Odisha states, is equivalent in intensity to a Category 4 hurricane in the Atlantic, or a supertyphoon in the Pacific. (It's 2 mph away from a Category 5 hurricane, the highest on the Saffir-Simpson Hurricane Wind Scale.)

It is not expected to make landfall until Friday morning in Odisha, near the city of Puri, but tropical cyclone-force winds are already coming ashore in portions of Andhra Pradesh and along the Odisha coast as well.

With winds expected to be 240 kilometers per hour (150 mph) at landfall, Tropical Cyclone Fani would be the strongest storm to hit the region since a similar system struck Odisha in 1999, resulting in at least 10,000 deaths.

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