US: High temperatures forecast to persist across southwestern regions through at least Aug. 6 /update 1

Forecast models indicate excessive temperatures are likely to persist across parts of the southwestern US through at least Aug 6. Highs of around 41-48 C (105-118 F) are likely across parts of northern, central, and southern Utah, southeastern Nevada, central and southeastern California, southcentral and western Arizona. The US National Weather Service (NWS) has warned of fire risks across large portions of the southwestern US over the coming days due to the combination of hot temperatures, low relative humidities, and low chances of precipitation.

As of early Aug. 4, the NWS has issued excessive heat warnings and advisories across the affected area. Minimum nighttime temperatures will also be well above average for the time of year, providing little relief from the excessive heat. 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 an increased 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 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, 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.