South America: High temperatures forecast to persist in far northern Argentina, south-central Brazil, and across Paraguay through at least March 20 /update 3

Forecast models indicate that high temperatures will persist across parts of far northern Argentina, south-central Brazil, and much of Paraguay through at least March 20. Temperatures exceeding 40 C (104) F are possible across parts of the affected area over the coming days.

As of early March 18, Argentina's National Meteorological Service (SENAMHI) has issued red high-temperature warnings (the highest level on a three-tier scale) across Formosa Province and parts of northwestern Chaco and eastern Salta provinces. Orange high-temperature warnings are in place for parts of northwestern Corrientes Province.

Brazil's National Institute of Meteorology (INMET) has issued a red heatwave warning (the highest level on a three-tier scale) across parts of central and southern Mato Grosso do Sul, northern Parana, and north-central and western Sao Paulo states. Orange heatwave warnings are in place across Rio de Janeiro and parts of southern Espirito Santo, southern Goias, northern Mato Grosso do Sul, southern Minas Gerais, and eastern, northern, and southern Sao Paulo states. Yellow heatwave warnings have been issued across central and western Minas Gerais State.

Paraguay's Directorate of Meteorology and Hydrology has warned of maximum temperatures of between 34-37 C (93-99 F) in the Eastern Region and around 40 C (104 F) in the Western Region March 18. A cold front moving across the country is forecast to bring cooler temperatures from March 21.

Officials could upgrade or expand the alerts as the heatwave develops over the coming days.

The high temperatures may result in increased energy and water demand and a heightened risk of heat-related illnesses, such as heat exhaustion and heat stroke.

The extended period of oppressive heat and dry conditions may produce ideal circumstances for further wildfire growth throughout the affected areas. 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.