Almost 300,000 people are set to be evacuated to 700 shelter homes, a spokesperson for India's Home Ministry said Wednesday. Schools and colleges in the area are closed until Friday, officials said.
Vayu passed about 300 kilometers (185 miles) west of Mumbai on Wednesday, moving north toward the Gujarat coastline.
The forecast calls for the storm to turn west, which could keep the center of the storm just offshore over the next 48 hours as it moves parallel to the Saurashtra Peninsula and Kutch district of Gujarat.
But even if the storm does not make an official landfall -- meaning the center, or eye, of the storm moves onshore -- at least half the storm will be over land, so the coastal region will be hit directly by rain, wind and storm surge.
India has deployed 39 National Disaster Response Force teams -- each with about 45 people -- to help local authorities with evacuation, search, rescue and relief operations. The army has 34 teams on standby.
Vayu formed Monday and strengthened on Tuesday into a hurricane-strength tropical cyclone in the Arabian Sea. Powerful tropical cyclones rarely make it this far north in the Arabian Sea, and Gujarat state has not had a hurricane-strength storm make landfall in 20 years.
Fisherman were warned about rough seas ahead of the storm's arrival. Coastal residents are preparing for a storm surge of up to 2 meters (6.5 feet), which could inundate parts of the low-lying coast of the Kutch district in Gujarat.
India's Meteorological Department is warning of the potential for heavy rainfall (over 200 millimeters or 8 inches) along with wind gusts over 135 kph along the Gujarat coast.
This is the second major tropical cyclone threat of the year for India, which faced Fani in early May.