Pack the sunglasses a little longer if you're heading to Portugal. After the hottest September since national records began, October is finishing well above normal too, and forecasters say the mild spell should hold for several more days. Santarém, in the Tejo valley north of Lisbon, could even touch 30°C on Friday.
The culprit is an anticyclone parked over the Azores. That high-pressure system is acting as a shield, blocking the Atlantic cold fronts and fierce storms churning out at sea from reaching the mainland. It is expected to keep doing that job until at least Sunday, which keeps conditions settled, dry and distinctly un-autumnal across much of the country.
There is a local name for this kind of weather. The Portuguese talk about 'St Martin's summer', a spell of warm days in early November tied to the feast of St Martin on 11 November. If the current pattern holds, this year's version could be warmer than usual. One caveat: while daytime temperatures stay summery, nights are cooling off noticeably. Expect pleasant t-shirt weather by day and a jumper or light jacket once the sun drops.
For travellers, this is quietly one of the best windows of the year. Summer crowds are long gone, accommodation prices have eased from their August peaks, and you can still swim, eat outdoors and tour towns like Santarém, Tomar or Lisbon without wilting in the heat. Beach resorts on the Costa Vicentina and in the Algarve remain viable for a late-season escape, while the Douro and Alentejo are at their most relaxed. Vineyard country is also buzzing right now — the grape harvest wraps up around this time, and many quintas offer tastings with fewer tour buses around.
Just keep an eye on the broader picture: the same Atlantic that is being held at bay by the anticyclone is producing serious storms offshore, and once that barrier weakens, the transition to classic wet autumn weather can be abrupt. If you're planning outdoor days — hiking in Sintra, cycling the Ecopista do Dão, a boat trip from Nazaré — build in a flexible schedule for the back end of your trip. Coastal walking trails may also stay closed on high fire-risk days, as late-season heat can keep wildfire warnings in force even in November.
In short: if a warm, quiet and relatively cheap week in Portugal appeals, this unusual autumn warmth is your invitation. Swap the winter sun of the Canaries for the real thing on the Iberian mainland — just bring layers for the evenings.
