Spain, Portugal: High temperatures forecast to persist over much of both countries through at least Aug. 12 /update 2

Forecast models indicate high temperatures will persist across much of Spain and Portugal through at least Aug. 12. Maximum temperatures in excess of 40 C (104 F) are possible across parts of the region over the coming days, with the peak of the heat likely Aug. 9-10. Temperatures will likely remain well above 20 C (68 F) at night across large parts of both countries. A cooler air mass is expected to move over the region Aug. 11-12, although high temperatures may persist in some interior parts of the Iberian Peninsula.

As of Aug. 9, the Spanish State Meteorological Agency (Agencia Estatal de Meteorologia, AEMET) has issued orange high-temperature warnings (the middle level on a three-tier scale) across parts of the interior of mainland Spain Aug. 9-11. Yellow warnings are in place across much of the rest of the interior and parts of the Balearic Islands.

The Portuguese Institute of the Sea and Atmosphere (IPMA) has issued red high-temperature warnings (the highest level on a three-tier scale) across Braganca, Guarda, and Vila Real districts Aug. 9-10. Orange high-temperature warnings are in place for Castelo Branco and Viseu districts Aug.9-10 and Braganca, Guarda, and Vsieu late Aug. 10-11. Yellow high-temperature warnings have been issued across Aveiro, Beja, Braga, Coimbra, Evora, Portalegre, Porto, Santarem, Setubal, and Viana do Castelo districts Aug. 9-10.

Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

The extended period of oppressive heat and dry conditions may produce ideal circumstances for additional wildfire growth throughout the region. Heatwaves also pose a threat to vulnerable groups - such as the elderly, children, pregnant women, and those with respiratory illnesses - due to the increased possibility of heat stroke or heat exhaustion during prolonged exposure to high temperatures. These health risks could also extend to relatively healthy individuals during significant heatwave events. In addition to significantly impacting athletes and those who work outdoors, high temperatures can cause problems for people using mass transit. The lack of air conditioning and cramped vehicles during rush hour may lead to some passengers being hospitalized for dehydration.

Very high temperatures may warp rail tracks and force passenger and freight trains to operate at reduced speeds. Road surface damage is also possible, and overheated vehicles may worsen traffic problems in urban areas where congestion is already a problem. Commercial trucking disruptions might occur, as very high temperatures put more stress on vehicles, making tire blowouts more common. Major flight disruptions are unlikely at regional airports, but general aviation disruptions are possible, and some airfreight carriers could reduce cargo loads. High temperatures could lead to an increased demand for electricity, which might trigger localized brownouts or blackouts, exacerbating hazardous conditions when air conditioning is no longer possible.