Lockdown requirements include restricting public gatherings to no more than five people.
Prime Minister Tuila'epa Sa'ilele Malielegaoi said individuals would be fined $US45 for their first offence and $US245 for a repeat.
Fines for organisations - including churches - are $US2,080, increasing to $US2,916.
Tuila'epa said people breaching the lockdown requirement would have the offence lodged as a criminal record which would affect overseas travel.
Meanwhile under the new lockdown requirements, inter-island passenger travel will be halted from midnight with ferries then only carrying goods and essential services staff.
Special flights will have been made today between Samoa and Fiji and American Samoa, to return those people to their homes and transport back Samoan students before the midnight lockdown.
Vessels bringing fuel and freight into Samoa were still allowed but new security measures apply.
Initially Samoa shut the border with American Samoa last Thursday when a state of emergency was announced but that left dozens of American Samoans stranded.
The US territory's governor, Lolo Matalasi Moliga, asked for special flights to be arranged to bring people back to Pago Pago.
Samoa Airways said it flew six flights with 14-16 passengers yesterday and operated more today.
All who return to Pago Pago are being transported to a quarantine facility for 14 days.