Eleven Districts Sit Under a Heat Warning Until Tuesday, and 62 Councils Are at Maximum Fire Danger Today

Eleven districts of mainland Portugal are under a yellow warning for high temperatures, and for most of them the warning runs until six on Tuesday evening. The Instituto Português do Mar e da Atmosfera lists the reason in the same five words for every district: persistence of high maximum temperature values.

The districts under warning are Braga, Bragança, Viana do Castelo, Vila Real, Porto, Aveiro, Coimbra, Leiria, Santarém, Lisboa and Setúbal. Lisboa and Setúbal come out of it on Monday evening; the other nine run through Tuesday. It is an unusual list, because it is essentially the coastal and northern half of the country rather than the interior that normally carries a September heat warning.

The numbers behind the warning

IPMA's own city forecasts show where this is heading. Coimbra is forecast to reach 35.8 degrees today, 36.8 on Monday and 37.0 on Tuesday, climbing as the week goes on rather than easing. Lisbon sits at 34.5 today and 35.4 on Monday. Porto reaches 32.8 today and again on Monday. Aveiro, which is under warning from nine this morning, is forecast at 31.3.

The relief, where it comes, arrives on Wednesday and comes from the north. Porto drops to a forecast 22.6 degrees on Wednesday and Aveiro to 20.5, a fall of ten degrees in a day. Lisbon and Coimbra stay warm into Wednesday. That is the shape of the thing: a hot weekend and a hotter Monday and Tuesday, then a sharp northern break that reaches the south late or not at all.

Fire danger is the more serious number

The heat warning is a comfort and health measure. The fire risk map is the one that decides how the week is staffed. IPMA's rural fire danger index for today places 62 of the 278 mainland councils at maximum danger and a further 139 at very high danger. That is three quarters of the country at one of the top two levels on a Sunday in late September.

Two fires this weekend show what that means in practice. More than 800 operational personnel were deployed against fires at Arganil and Vila Nova de Poiares in the Coimbra district, and the Arganil fire left firefighters injured before it was brought under control early this morning. A separate fire forced the A1 to be closed in both directions near Aveiro on Friday.

What this means for you

• Yellow is not nothing. A yellow warning is the level at which IPMA expects a risk to specific groups rather than to everyone. Older people, very young children, people with cardiac or respiratory conditions and anyone working outdoors are the groups it is drawn for.
• The heat is arriving after the season ended. Municipal cooling points, extended pool hours and summer fire-service rosters are often wound down in mid-September. Do not assume the support that existed in August is still there this week.
• Check the fire index before you travel inland. IPMA publishes the risk by council each morning at ipma.pt. At maximum danger, lighting any fire, using strimmers and chainsaws in or near woodland, and burning cuttings are all restricted or banned.
• Respect road closures without argument. The A1 closure near Aveiro was a live example. Motorway closures during a fire are about smoke visibility and giving aircraft a water-drop corridor, not about the flames reaching the carriageway.

Portugal's heat episodes are now measured in deaths as well as degrees: the national health institute attributed an estimated 680 excess deaths to three heat spells this summer. A late-September warning across eleven districts is a reminder that the risk window in Portugal no longer closes when the school year starts.