According to the list which is updated every three weeks, the British government only requires passengers from the Azores to submit to a Covid-19 test before departure and another in England when travelling between the two countries.
The Azores will thus join the Autonomous Region of Madeira, as of 4:00 am on Monday, which was added to the green list at the end of June.
Mainland Portugal remains on the Amber list.
Travellers arriving in England from a country on the amber list and already having full covid-19 vaccination must undergo two screening tests, one before travel and one on arrival, and are exempt from quarantine.
Unvaccinated travellers or travellers with incomplete vaccinations must undergo two PCR tests within the first eight days of arrival and complete a 10-day isolation period.
As of Monday, Canada, Denmark, Finland, Lithuania and Switzerland will also be included on the green list.
Thailand and Montenegro, by contrast, are now on the red list, which means that in addition to having to test negative on arrival, they also have to stay in mandatory isolation in accommodation chosen by the British government, which costs €2,660.