Perth Airport is bracing for an influx of interstate passengers when Western Australia's hard borders finally reopen over the weekend.

Western Australia's borders will finally reopen on Saturday after seven long months, with Premier Mark McGowan declaring the time is right.

About 2000 passengers, including those from overseas, are expected to arrive at Perth Airport over the weekend as the state welcomes back interstate travellers.

"Western Australia is ready to take the next step forward," the premier said on Friday.

"Our controlled interstate border is a cautious and safe step. It is balanced and sensible.

"The time is right."

People who have recently been in NSW or Victoria will be required to self-quarantine for 14 days at a suitable premises under the new "controlled border" regime.

They will also be required to undertake COVID-19 tests upon arrival and on day 11 of their quarantine period.

Arrivals from all other states and territories - deemed "very low risk" jurisdictions - will not be required to quarantine but must undergo health screening, a temperature check and complete an application declaring their recent travel.

Perth Airport is expected to handle up to 20 interstate flights over the weekend compared to just five last weekend.

"Let me be clear, there will be delays at the airport," Mr McGowan said.

"These controls are unprecedented and will be frustrating for many people."

Perth Airport chief executive Kevin Brown says people arriving from Sydney and Melbourne will be processed separately to other passengers.

"It's certainly going to be a bit busier this weekend," he told Perth radio 6PR.

"We're probably only about a quarter of the number of passengers that we'd normally put through the terminals so still a long way to go."

Others will arrive via road, with families and seasonal workers already trekking across the Nullarbor towards the South Australian border.

Police have warned that anyone failing to disclose recently travelling through NSW or Victoria faces a large fine or potentially even imprisonment.

The quarantine requirement for those states will only be removed once they go at least 28 days with no community spread, as all other jurisdictions have achieved.

Victoria has now gone 14 days with no new cases.

"It's not automatic that at 28 days, Victoria instantly becomes (lower-risk)," Mr McGowan said, adding that WA - unlike other states - would not be targeting a Christmas deadline for the resumption of all domestic travel.

"We'll take health advice closer to that date and make a decision based on the circumstances at that time."

All arrivals must complete a G2G application and adhere to health requirements.

WA implemented a hard border regime in early April, denying entry to anyone except required workers and individuals granted exemptions on compassionate grounds.

The state recorded no new COVID-19 cases on Friday.