US: High temperatures forecast to persist across southwestern regions through at least Oct. 4

Forecast models indicate excessive temperatures will persist across parts of the southwestern US through at least Oct. 4. Temperatures of around 35-46 C (95-115 F) are forecast across the affected area over the coming days. As of early Sept. 30, the National Weather Service (NWS) has issued excessive heat warnings across parts of western Arizona, far southern Nevada, and northwestern and southeastern California. Excessive heat watches and heat advisories are in place across parts of southwestern and western California. Officials could update and extend the coverage of weather alerts over the coming days.

The high temperatures may result in increased energy and water demand and a higher risk of heat-related illnesses such as heat exhaustion and heat stroke. Authorities advise the general public to avoid prolonged exposure to direct sunlight, wear loose and light clothing, and stay hydrated.

The extended period of oppressive heat and dry conditions may produce ideal circumstances for 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.

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 an issue. Commercial trucking disruptions might occur as very high temperatures put more stress on vehicles, making tire blowouts more common. Major flight disruptions are unlikely, 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.