Portugal: Heatwave forecast across mainland areas through at least Aug. 5

Event

Forecast models indicate a heatwave will persist across parts of mainland Portugal through at least Aug. 5. The Portuguese Institute of the Sea and Atmosphere (IPMA) has forecast that temperatures will begin to rise across much of the country July 29-31, with an especially sharp rise in northern and central coastal areas July 30-31. Maximum temperatures are expected to reach 40-42 C (104-108 F) in the Douro and Tagus valleys as well as some central and southern interior regions July 30-31. Temperatures of 35-40 C (95-104 F) are expected across the rest of the mainland, with the exception of some coastal areas where temperatures will be slightly cooler, especially along the south coast. Temperatures are forecast to drop slightly in northern and central coastal areas from Aug. 1; however, the heatwave is expected to persist in northern and central interior regions through Aug. 5.

As of July 29, the IPMA has issued the following warnings across mainland Portugal July 30-31:

• Orange high-temperature warnings (the middle level on a three-tier scale): Barga, Braganca, Castelo Blanco, Guarda, and Vila Real districts.

• Yellow high-temperature warnings: Aveiro, Beja, Coimbra, Evora, Leiria, Lisboa, Portalegre, Porto, Santarem, Viana do Castelo, and Viseu districts.

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

Hazardous Conditions
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.

Transport and Utilities
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 engines, 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.

Advice

Monitor local media for weather updates and related advisories. During heatwaves, remain indoors in air conditioning when possible. If outdoor activities are necessary, frequently rest in shaded areas; avoid activity during the hottest times of the day. Stay well-hydrated by drinking plenty of fluids. Avoid alcoholic beverages, which are dehydrating; drink water that is bottled or has been boiled. Wear loose-fitting, light-colored clothing. Cotton fabrics are more cooling than synthetics. Promptly seek medical attention if signs of heat exhaustion or heat stroke develop. Charge battery-powered devices in case prolonged electricity outages occur.

Resources

MeteoAlarm
Portuguese Institute of the Sea and Atmosphere (IPMA)