All communication to Fiji's remote southern Lau Islands is currently cut off, Fiji's Disaster Management Office says.
Two islands in the nearby southern Lau group, Ono-i-Lau and Vatoa, are facing a direct hit.
Director for Fiji's National Disaster Management Office Anare Leweniqila said the cyclone was now hitting Ono-i-Lau island.
"Right now they are feeling the brunt of Tropical Cyclone Gita. We have also lost all communications with the island and we are currently awaiting the tropical cyclone to pass before we try to re-establish contact with them."
Prior to communications going down, the office had received reports of swells and been told that people had started moving to evacuation centres - including a school, a post office and a health centre.
He said officials expected Ono-i-Lau island and other islands in the red zone to be "badly affected".
The government was now moving to a response phase.
The Fiji Met Office is forecasting average wind speeds of 195km/hour and gusts up to 275km/hour for Ono-i-Lau and Vatoa.
The medical officer for the island group said if remote islands lose telephone contact due to Cyclone Gita they will lose direct contact with doctors.
Dr Dexter Chute, who is based at Lakeba Hospital, said nursing staff on Vatoa and Ono-i-Lau rely upon telephone instruction for serious medical cases.
Without radio and telephone contact, communities will rely upon the well-trained and resourceful nursing staff, Dr Chute said.
Meanwhile, residents on other islands are preparing for the oncoming cyclone.
Talica Vuki lives in Taliva Village on Kadavu Island, the fourth largest island in Fiji and 88 kilometres south of the capital, Suva.
She was preparing for a category five cyclone but had chosen not to evacuate because she lived inland and her house, despite being made of tin, survived Cyclone Winston.
She was tying knots on the roof to try and stop the roof from flying off when the cyclone hit.
"Some people have been going to evacuation centres - there's a school here...some are going to evacuate there, and some are going to the community hall, those near the shores," she said.
Evacuation centres have been set up all over Kadavu Island and its neighbours. Even on the mainland, where winds are currently not expected to break 80 km/hr - people are preparing - Cyclone Winston, almost two years ago to the day, is still a vivid memory for many.
Australian-born Sue Churchill, who lives in Ba, northwest of mainland Fiji, moved to the country seven years ago to retire. She didn't have power for five months after Winston.
"My house still hasn't been fully repaired. My roof, while it's still on and intact - I'm waiting for next door to bring wire down to tie across the roof where one of the ties broke after Winston. We've moved sheets of tin undercover and put big rocks on them to hold them down," she said.
She said some people were still recovering from Tropical Cyclone Winston.
"There are still people in Fiji living in tents, that haven't had their houses rebuilt or repaired. Winston's still affecting people so people are very much more aware now and taking notice."
However, Tanya Ali, who lives in the capital, Suva, said she did not feel like a cyclone was headed for Fiji.
"I just drove through town - there's supermarkets open - the roads are clear... Usually, If they were taking it seriously they would be at petrol stations filling cars and at shopping centres and stuff but it's pretty clear right now.
"So what happens if it does an about turn like Winston did? Then what? There haven't been any notices of closure of offices and stuff - I haven't seen anything."
She said people were still expecting to go to work tomorrow and schools were still open.
But Sue Churchill said that if Cyclone Gita moved just a few hundred kilometres north, the story could be very different.
"I heard this morning that when it hit Tonga it was more powerful than Hurricane Harvey when it hit Texas last year and that was still at category four. So if it becomes category five as they expect it to, we're up shit creek without a paddle as they say - we're in trouble," she said.