HONOLULU -- Hawaii's governor asked Monday that visitors and residents reduce travel to the islands to essential business only while the state struggles to control COVID-19 as the highly contagious delta variant spreads in the community.

Gov. David Ige wants to curtail travel to Hawaii through the end of October.

"It is a risky time to be travelling right now," he said.

He said restaurant capacity has been restricted and there's limited access to rental cars.

Ige stopped short of a mandate, saying it's a different time now than last year when strict travel rules that required quarantining essentially shut down Hawaii's tourism industry.

"Last year in March, when I first asked for visitors to postpone travel to the islands, we saw a 60 per cent reduction in the traffic to Hawaii" Ige said. "And then certainly, ordering the mandatory quarantine of all incoming visitors reduced travel to the islands by 99.5 per cent, essentially 100 per cent of travellers."

Things are different now with vaccines available and guidance from the Centers for Disease Control and Prevention saying fully vaccinated people can travel domestically.

Ige said he supports Honolulu Mayor Rick Blangiardi's announcement to restrict indoor gatherings to 10 people and outdoor gatherings to 25.

Blangiardi said the rules taking effect Wednesday would apply to weddings and other events.

He's also urging people to get vaccinated.

Hiro Toiya, the city's emergency management director, cited a mathematical modeling tool from the Georgia Institute of Technology to illustrate risks the community faced from large gatherings.

The modeling shows there is a 20 per cent chance that someone in a group of 10 will have the disease given the number of COVID-19 cases on Oahu now. But in a group of 100, there's a 90 per cent chance someone will have it.

"So when you're looking at how transmissible delta is, we really got to control these large gatherings," Toiya said at a news conference. "The status quo is not working, and it's not acceptable."

Multiple Oahu hospitals have filled their regular beds as COVID-19 cases pour into emergency rooms. The city set up a 25-cot tent outside The Queen's Medical Center - West Oahu on Friday to help handle the influx.