Many UK holidaymakers in Portugal, or booked to travel there, are watching anxiously to see if quarantine will be imposed by the authorities in England and Northern Ireland.
Scotland and Wales already impose two weeks of self-isolation on travellers returning from Portugal, though Wales gives exemption to the islands of Madeira and the Azores.
In the past 24 hours, Portugal has recorded 388 new cases of coronavirus, taking the rate of fresh infections per 100,000 people over the past week to 25.8.
The government’s stated threshold for imposing quarantine is 20; the UK currently stands at 23.1 on the same measure.
Many observers were expecting Portugal to be placed on the UK government’s “no-go” list last weekend, but the transport secretary, Grant Shapps, gave the country a reprieve – saying that the rising numbers of cases was a result of sharply increased testing.
But with increasing concern in central government about infection rates, it looks likely that Portugal will lose its short-lived exemption in the regular Department for Transport update on Thursday evening.
Madeira and the Azores are likely to remain on the exempt list, whatever happens.
If quarantine is re-imposed, English and Northern Irish holidaymakers are likely to be faced with the choice of a fast and expensive dash for home by 4am on Saturday, or self-isolating for 14 days on their return.
Many travellers paid hundreds of pounds for flights from Portugal last Friday ahead of an expected announcement.
This week, though, British Airways is selling seats on its three Friday departures from Faro – the main airport for the Algarve coastal region – to London Heathrow for around £60 one way.
Were Portugal to be judged “unacceptably high risk,” the number of autumn sun destinations will shrink still further. With France, Spain, Croatia and some or all of Greece already on the no-go list, many holidaymakers are heading for Italy, Cyprus and Turkey.
Italy, which as recently as a week ago was considered a model of excellence because of its low new-infection rates, is now close to the 20-case threshold. At the current rate of increase, it will reach the figure within two weeks.
Turkey is seeing new case numbers slowly rising, but is thought to be “safe” for at least the rest of September.
Denmark is now on the danger list, with 21.9 cases per 100,000 inhabitants over the past week.
Fares for flights from Copenhagen are soaring, with easyJet’s evening departure for Manchester on 11 September selling for £247 – for a 620-mile flight lasting under two hours.
Were quarantine to be imposed on Denmark, though, many travellers would be able to find an alternative via one of the key German cities such as Hamburg, Bremen or Berlin.